We investigated the eventual positive effects of early screening and treatment for varicocele in pubertal boys without symptoms to determine their chance of paternity later in life. It has not been proved if the presence of varicocele during puberty has an influence on later fertility or paternity. However, since an influence is believed to exist, beginning in 1987 the Belgian Society of Pediatrics has recommended screening all boys 12 to 17 years old during their yearly medical examination and referral for followup or treatment if varicocele is detected. At our clinic patients and their parents were informed about and able to choose between varicocele treatment (antegrade sclerotherapy) and observation. We subsequently contacted these patients, who are now older than 30 years, and inquired about their paternity.