Despite the cremaster's important role in thermoregulation, few morphological and biochemical studies of this muscle in humans have been reported, probably due to limitation of sampling. To gain further insight into the pathology of varicocele, the authors studied the histochemical changes of the cremaster from patients with varicocele. Cremaster was obtained from patients with male infertility and varicocele, grades 1-3. The samples were studied using routine histochemical stains. Fiber size variability and type I predominance were observed in all varicocele cases regardless of the grade, and also in control specimens. Muscle from patients with grades 2 and 3 varicocele showed small group atrophy. It would appear that the hemostasis associated with local tissue edema and hypoxemia may lead to nerve damage and denervation of the cremaster. If denervation of the cremaster persists despite the correction of varicocele, thermoregulation would remain disrupted.