Intercomparison and validation of computer codes used in different countries for thermohydraulics safety analysis of heavy water reactors (HWRs) enhances confidence in the predictions made by these codes. A set of reliable experimental data is necessary for conducting such intercomparison and validation exercises. Experimental results from a large loss of coolant accident (LOCA) test simulating HWR LOCA behaviour that was conducted by Atomic Energy of Canada Ltd (AECL) was selected for this validation project. This report provides a comparison of the results obtained from six participating countries, utilizing four different computer codes. General conclusions are reached and recommendations made.