Objective To determine the sperm acrosome integrity of samples from infertile men with varicocele.Methods Forty-nine infertile men with varicocele were divided into three groups according to the grade of varicocele. Group A (grade Ⅰ), B (grade Ⅱ), and C (grade Ⅲ) consisted of 15, 18, and 16 cases, respectively. Besides, 15 semen samples from normospermic donors were used as the control. The acrosome integrity of sperm was examined with fluorescein-labeled Pisum sativum agglutinin. Acrosomal ultrastructure was observed with transmission electron microscopy.Results In three varicocele groups, most samples had high sperm abnormal morphology rates. There were significant differences in acrosome integrity rates between each varicocele group and the control (P＜0.01). Group C had the lowest acrosome integrity rate among the three groups. Ultrastructural observation showed that acrosome malformations revealed acrosomal membranes defects, swelling, hypoplasia, and dissolution of the matrix.Conclusions Infertile men with varicocele had low level of acrosome integrity. Severe varicocele for infertile men might be associated with severe acrosomal defects. Evaluating sperm acrosome should aid the understanding of the sperm structural state and benefit the treatment for infertile men.