diff --git a/opm/autodiff/FlowMain.hpp b/opm/autodiff/FlowMain.hpp
index aa613c890..a1fb5e05b 100644
--- a/opm/autodiff/FlowMain.hpp
+++ b/opm/autodiff/FlowMain.hpp
@@ -84,6 +84,8 @@
 
 #include <boost/filesystem.hpp>
 #include <boost/algorithm/string.hpp>
+#include <boost/filesystem/fstream.hpp>
+#include <boost/regex.hpp>
 
 #ifdef _OPENMP
 #include <omp.h>
@@ -109,6 +111,101 @@ namespace Opm
     {
         boost::filesystem::path simulationCaseName( const std::string& casename );
         int64_t convertMessageType(const Message::type& mtype);
+
+        namespace fs = boost::filesystem;
+
+    /// \brief A functor that merges multiple files of a parallel run to one file.
+    ///
+    /// Without care multiple processes might log messages in a parallel run.
+    /// Non-root processes will do that to seperate files
+    /// <basename>.<rank>.<extension. This functor will append those file
+    /// to usual ones and delete the other files.
+    class ParallelFileMerger
+    {
+    public:
+        /// \brief Constructor
+        /// \param output_dir The output directory to use for reading/Writing.
+        /// \param deckanme The name of the deck.
+        ParallelFileMerger(fs::path output_dir,
+                           const std::string& deckname)
+            : debugFileRegex_("\\."+deckname+"\\.\\d+\\.DEBUG"),
+              logFileRegex_(deckname+"\\.\\d+\\.PRT")
+        {
+            auto debugPath = output_dir;
+            debugPath /= (std::string(".") + deckname + ".DEBUG");
+            debugStream_.reset(new fs::ofstream(debugPath,
+                                                std::ofstream::app));
+            auto logPath = output_dir;
+            logPath /= ( deckname + ".PRT");
+            logStream_.reset(new fs::ofstream(logPath,
+                                              std::ofstream::app));
+        }
+
+        void operator()(const fs::path& file)
+        {
+            const static boost::regex regex(".+\\.(\\d+)\\..+");
+            boost::smatch matches;
+            std::string filename = file.filename().native();
+
+            if ( boost::regex_match(filename, matches, regex) )
+            {
+                std::string rank = boost::regex_replace(filename, regex, "\\1");
+
+
+                if( boost::regex_match(filename, logFileRegex_) )
+                {
+                    appendFile(*logStream_, file, rank);
+                }
+                else
+                {
+                    if (boost::regex_match(filename, debugFileRegex_)  )
+                    {
+                        appendFile(*debugStream_, file, rank);
+                    }
+                    else
+                    {
+                        OPM_THROW(std::runtime_error,
+                                  "Unrecognized file with name "
+                                  << filename
+                                  << " from parallel run.");
+                    }
+                }
+            }
+        }
+    private:
+        /// \brief Append contents of a file to a stream
+        /// \brief of The output stream to use.
+        /// \brief file The file whose content to append.
+        /// \brief rank The rank that wrote the file.
+        void appendFile(fs::ofstream& of, const fs::path& file, const std::string& rank)
+        {
+            if( fs::file_size(file) )
+            {
+                std::cerr<<"WARNING: There has been logging out by non-root process "
+                         <<rank<<std::endl<<"Please report this in the issue tracker!"
+                         <<std::endl;
+                fs::ifstream in(file);
+                of<<std::endl<< std::endl;
+                of<<"=======================================================";
+                of<<std::endl<<std::endl;
+                of<<" Output written by rank "<<rank<<" to file "<<file.string()<<":"<<std::endl<<std::endl;
+                of<<in.rdbuf()<<std::endl<<std::endl;
+                of<<"======================== end output =====================";
+                of<<std::endl;
+                in.close();
+            }
+            fs::remove(file);
+        }
+
+        /// \brief Regex to capture .*.DEBUG
+        boost::regex debugFileRegex_;
+        /// \brief Regex to capture  *.PRT
+        boost::regex logFileRegex_;
+        /// \brief Stream to *.DEBUG file
+        std::unique_ptr<fs::ofstream> debugStream_;
+        /// \brief Stream to *.PRT file
+        std::unique_ptr<fs::ofstream> logStream_;
+    };
     }
 
 
@@ -152,7 +249,11 @@ namespace Opm
             asImpl().createSimulator();
             
             // Run.
-            return asImpl().runSimulator();
+            auto ret =  asImpl().runSimulator();
+
+            asImpl().mergeParallelLogFiles();
+
+            return ret;
         }
         catch (const std::exception &e) {
             std::ostringstream message;
@@ -390,12 +491,14 @@ namespace Opm
                 baseName = path(fpath.filename()).string();
             }
             if (param_.has("output_dir")) {
-                logFileStream << output_dir_ << "/" << baseName + ".PRT";
-                debugFileStream << output_dir_ + "/." + baseName + ".DEBUG";
-            } else {
-                logFileStream << baseName << ".PRT";
-                debugFileStream << "." << baseName << ".DEBUG";
+                logFileStream << output_dir_ << "/";
+                debugFileStream << output_dir_ + "/";
             }
+
+            logFileStream << baseName;
+            debugFileStream << "." << baseName;
+
+            if ( must_distribute_ && mpi_rank_ != 0 )
             {
                 // Added rank to log file for non-zero ranks.
                 // This prevents message loss.
@@ -403,6 +506,9 @@ namespace Opm
                 // If the following file appears then there is a bug.
                 logFileStream << "." << mpi_rank_;
             }
+            logFileStream << ".PRT";
+            debugFileStream << ".DEBUG";
+
             std::string debugFile = debugFileStream.str();
             logFile_ = logFileStream.str();
 
@@ -422,10 +528,29 @@ namespace Opm
             }
         }
 
+        void mergeParallelLogFiles()
+        {
+            // force closing of all log files.
+            OpmLog::removeAllBackends();
 
+            if( mpi_rank_ != 0 || !must_distribute_ )
+            {
+                return;
+            }
 
+            namespace fs = boost::filesystem;
+            fs::path output_path(".");
+            if ( param_.has("output_dir") )
+            {
+                output_path = fs::path(output_dir_);
+            }
 
+            fs::path deck_filename(param_.get<std::string>("deck_filename"));
 
+            std::for_each(fs::directory_iterator(output_path),
+                          fs::directory_iterator(),
+                          detail::ParallelFileMerger(output_path, deck_filename.stem().string()));
+        }
 
         // Parser the input and creates the Deck and EclipseState objects.
         // Writes to: