A total of 20 male patients 11 to 19 years old had a grade 2 or 3 varicocele and volume loss of the testis ipsilateral to the varicocele. None of these patients presented because of subfertility. Following varicocele ligation a significant increase in volume of the testis ipsilateral to the varicocele was observed in 16 of 20 patients. All 20 patients have been followed for 1 to 6 years. Our results suggest that a moderate to large varicocele can be responsible for testicular growth retardation and that early ligation of the varicocele may reverse this process.