As with the other monographs of the American Lecture Series, Dr. Heckel tries to present a complex subject in a concise but abbreviated form. This type of presentation has many shortcomings in a field where so much controversy exists in regard to diagnosis, treatment, and even basic gonadal physiology. It has not been firmly established, for instance, that orchiopexy or even gonadotropin treatment of cryptorchism is a clinically justified procedure as Dr. Heckel would advocate. Again, one might take issue with the statement that "testosterone is produced by the Leydig cells." The physiological Leydig-cell androgen has not been established. In general, however, this short monograph is well presented and written and should be useful to the general practitioner.