The abilities of two isolates of Tritrichomonas foetus to survive and replicate in transport and Diamond's medium or in the InPouch TF system (Bio-Med Diagnostics) when exposed to different temperatures for different periods were determined in a series of experiments. Tubes containing thioglycollate transport medium or pouches were inoculated with 4000 to 5000 organisms and kept for up to seven days at 37 degrees C, 22 degrees C, 4 degrees C, or -20 degrees C. When the holding time had elapsed, the numbers of motile T foetus were counted. Samples in transport medium were transferred to Diamond's medium, and both the pouches and tubes containing Diamond's medium were incubated at 37 degrees C. The cultures were examined and counted four or five times during the 10 to 14 day culture period. The sensitivity of the test under the different conditions, expressed as the number of positive cultures/the total number of samples x 100, varied from zero to 100 per cent depending upon the combination of variables considered. In each medium, with both isolates of T foetus, all samples kept for up to four days at 22 degrees C or 37 degrees C were positive. All cultures of samples kept more than five days at 4 degrees C were negative. No positive cultures were detected when samples were kept more than three hours at -20 degrees C. The day on which the cultures reached mean peak concentration varied with the temperature at which the samples had been kept before they were cultured.