A method for the determination of the tritium distribution in environmental and biological samples is described. Tritium as HTO is removed by freeze-drying and the residue is combusted to obtain organically bound tritium. Each tritium fraction is electrolytically enriched and determined by liquid scintillation spectrometry. Enrichment and large sample sizes are required due to the low environmental tritium levels. During the analyses of more than 600 samples over a two-year period all aspects of the method (freeze-drying, combustion, enrichment and counting) have provided reproducible and precise results.