Varicocele is detected in about one-third of men with subfertile semen quality. Treatment by means of transcatheter embolization using the tissue adhesive Histoacryl improves Sertoli cell function with increased concentrations of transferrin in semen, and a significant increase in sperm concentration, normal morphology and linear velocity. Failure to attain pregnancy after varicocele treatment occurs if pre-treatment sperm quality is normal, or in the case of azoospermia with elevated blood FSH levels or obstruction, or when there is severe coincidental pathology impairing fertility of the male or female partner. In all other cases, the poor results of varicocele treatment reported in some studies can only be explained by inadequate techniques. Varicocele detection and embolization treatment at puberty or during adolescence should be advocated to prevent deterioration of testicular function.