Artificial insemination using the husband's semen (AIH) can help overcome a number of cases of sterility, particularly where these are male in origin. But the results are not always in proportion to the effort required, both from the patients and their doctor. We have compared 25 cases in which AIH resulted in pregnancy with 25 cases in which no pregnancy was achieved after a minimum of 6 cycles' insemination. No factor other than success or failure entered into the selection of cases for comparison. No significant difference was observed in age, past medical history, clinical findings and treatment used. However, study of the seminal analyses showed that the number of spermatozoa was only a secondary factor; sperm motility, and its duration, were more important. This gave two graphs defining two prognostic zones. In 72% of cases, pregnancy was achieved during the first 5 cycles of insemination using AIH. Lastly, miscarriages increased in frequency with age. The number of cases studied is obviously too few to provide any binding statistical conclusions, but these preliminary results give grounds for continuing the study; mathematical models ought to make it possible to identify prognostic factors.