The effect of long-term driving upon spermiogenesis was investigated in 2984 patients, including 281 professional drivers. The incidence of pathospermia was significantly increased among the 281 occupational drivers as compared to other professionals. The ratio of severe pathospermia was increased in proportion to the number of years of driving. The deterioration of spermiogenesis was mild among car drivers, but was severe in agricultural-industrial hard machinery and farm equipment drivers. There was a higher incidence of impaired fertility in drivers as compared to other professionals. The possible factors influencing these results are discussed.