Introduction: Isolated teratozoospermia is rarely encountered in patients with clinically palpable varicocele, and the consequences of varicocelectomy remain unclear in these cases. In the current study, we assessed the effect of varicocelectomy on sperm morphology in a series of patients with infertility. Materials and Methods: The data obtained from 52 primary subfertile men with isolated teratozoospermia and clinical palpable varicocele were reviewed retrospectively. Varicocelectomy was performed on 29 patients, and the remaining 23 patients did not undergo any treatment ( control group). The differences in sperm morphology assessed by using Kruger's strict criteria 3 months before and 12 months after varicocelectomy were taken into consideration for statistical analysis. Results: One patient who underwent varicocelectomy was excluded from the study due to varicocele recurrence. Thus, data obtained from the remaining 28 patients were evaluated. Following varicocelectomy, significant improvement was detected in the ratio of normal sperm forms (p < 0.001). While there was significant improvement in the ratio of sperm cells with head defects, tail defects and immature forms ( p < 0.001), the ratio of sperm with acrosome and mid- piece defects was not changed (p > 0.05). While an overall spontaneous pregnancy was achieved in 5 of the 28 ( 17.8%) couples in the varicocelectomy group within 12 months after operation, neither improvement in sperm morphology nor pregnancy in the patients' partners was deected in the control group. Conclusion: Varicocelectomy caused a significant improvement in sperm morphology, particularly in immature forms and forms with head and tail defects evaluated by Kruger's classification. Copyright (C) 2008 S. Karger AG, Basel.