Hamster tests were performed on sperm samples submitted by 111 men attending a fertility clinic. The method used involved exposure of the sperm to an ionophore to stimulate capacitation as this has been shown to give better egg penetration rates. The men were followed up for a total of 166 couple years and note was made of any pregnancies. At the time of their initial assessment most of the men had poor sperm measurements using conventional methods of semen analysis. The hamster test results gave no additional prognostic information to that already known from the duration of involuntary infertility reported by the couple at their first clinic visit and sperm motility and concentration determined by conventional semen analysis. It was concluded that the hamster test was not useful in this situation.