The experimental methods employed at the La Jolla Natural Tritium Laboratory, University of California, for the determination of natural tritium are briefly described. The method is to assay the electrolytically enriched sample as ethane gas in a proportional counter. An error of less than 4% is obtained for samples enriched by reducing the sample volume from 2 liters to 10 ml. It is found that the previous methods of calculating the electrolytic enrichment are not necessary nor are large volume reductions necessary for most applications. In the method adapted at La Jolla the enrichment in five electrolysed samples is determined by using a sixth spiked sample. In this way it is shown that the enrichment in the sixth sample is within 4% of the enrichment in the other five and can be quickly determined.