The effect of caffeine (C) and pentoxifylline (P) on the sperm motility was examined after a 3 degrees C storage in a TEST yolk buffer for one week. Thus stored 24 semen samples from infertile patients were incubated with or without C or P at 37 degrees C. The motility was analysed for up to 240 minutes. The poststorage addition of C (1 mM) and P (1 mM) significantly increased the serum motility rate (p < 0.01). The stimulant effect of C and P was rather transient lasting no more than 2 hours. The prestorage addition of C and P in a preservant TEST yolk buffer was less effective than the poststorage administration. According to the time-related profiles of the sperm motility, 24 cases were divided into three groups. In group A (11 cases), the sperm motility rate increased from 30 to 90 minutes even without C or P. This group was responder of C and P. In group B (8 cases), the motility rate increased only in response to C and P and, in group C (5 cases), no such responses were observed. The prestorage semen qualities in terms of the sperm concentration, the motility rate, the velocity, the linearity, and the amplitude of the lateral head displacement were compared in these three groups. There was a significant difference between these 3 groups (p < 0.05) on the parameters in terms of the sperm concentration, motility rate and velocity. It was suggested that these prestorage parameters predict the sperm activity in response to C and P after a one week 3 degrees C storage.