The goal of this study is to determine the effect of heat on seminal fluid among Sudanese laborers who work in increased temperature working conditions. Since the scrotal temperature is maintained 2-3 C lower than the body temperature. This is an important pre-requisite for optimal spermatogenesis. Thus the effect of higher temperature needs to be evaluated. Some Sudanese laborers work in very hot environment like boiler, turbines, maintenance, and operation sections in thermal power stations (Elshaheed and Garri) in Khartoum state. Those laborers were exposed to high occupational heat 50-120 C. Thirty five subjects were included in this study. Their ages were between 26 and 52 years of age. Their spend a duration from 1 year up to 30 years, with daily exposure to high temperature risk from 2 to 12 hours. Semen samples were taken from all subjects. The semen sample analyzed by Computer Assisted Sperm Analysis (CASA) method. The entire semen samples had normal color, PH, volume and appearance. Abnormal parameters appeared in semen concentration, motility, viscosity and morphology.