Cryptorchidism is likely a major cause of male infertility, although there are no controlled studies of formerly unilateral or bilateral cryptorchid males. It is not known whether fertility is related to the age of treatment of cryptorchidism, pretreatment testicular location and pretreatment size. There is no evidence that orchidopexy effects subsequent fertility. In spite of the lack of evidence, the current recommended age to correct cryptorchidism by age 2 is virtually universally accepted. There is a cohort of 2000 formerly cryptorchid males now 21 years of age or older who had surgery during childhood at The Children's Hospital of Pittsburgh between 1955 and 1984. This group is unique because it includes a large group of patients who had surgery at age 2 or younger so the relationship to age of treatment can be assessed even among those treated at very young ages. In this cohort it is estimated that 900 will be married, able to be contacted and willing to participate in an assessment of paternity. This project will evaluate these subjects to ascertain: 1. If infertility expressed as paternity is decreased in formerly unilateral and bilateral cryptorchid. 2. If there is a relationship between the age of treatment pretreatment testicular location, size, the presence of a biopsy and paternity. External controls will be used for portion one, fertile subjects will serve as internal controls in portion two. Patient availability has been ascertained to a subset of the population; 2145 subjects of the projected 3750 have been identified from the most recent 25 years of the 30 year period from 1955 to 1984. The research investigators are those who have been involved in a very successful epidemiologic study of former Children's Hospital patients with diabetes mellitus. A pilot study of 350 medical history records has verified the availability of subjects and reliability of data. A subset of 25 subjects have been contacted with initial data collection demonstrating a sampling of data and reassurance that data can be obtained. This study will, evaluate fertility in cryptorchidism and determine if treatment of bilateral or unilateral cryptorchidism effects fertility.