Exposure to electromagnetic fields (EMFs) is unavoidable for almost all citizens living in industrialized countries. Static magnetic fields (SMFs) can be encountered in a number of workplaces and situations. Power stations produce a range of magnetic fields more than 20 mT which are harmful to those working or living around them. Several investigators have reported an increased health risk due to exposure to electric and magnetic fields (EMF) at 50 and 60 Hz. Several studies have been reported especially with increased tumor incidence, effects on reproduction and development, and neural and behavioral changes. This study evaluated the possible effect of SMFs 50 Hz on the secretion of testosterone, FSH and LH in the male rat. We performed two series of experiments. In the first experiment 48 Wistar male rats (same range of age and weight) were randomly divided into four groups. Animals in group 1 were used as a sham exposure group. After 1 week adaptation they were placed into three SMFs exposure for 40 min daily for 17 days. Groups 2, 3 and 4 were exposed with 6, 12 and 24 mT SMFs at 50 Hz respectively. The second series of experiments was similar to the first experiments, except that the duration of SMFs exposure was for 2 h instead of 40 min daily. After experiments, animals were anaesthetised with diethyl ether, their blood was collected in separate tubes and they were humanely killed. Serum was removed and kept frozen at -20^oC until use. Hormones were measured using a gamma counter and with IRMA and RIA methods. The results were analyzed by ANOVA. Data from the first part of the study showed that testosterone, FSH and LH did not change significantly using the short duration SMFs. However, data from the second part of the study showed that testosterone and LH changed significantly (p<0.05) using longer duration SMFs but that the FSH level did not change significantly. In conclusion long term exposure of low intensities of SMFs can affect hypothalamic-pituitary-gonadal hormonal concentrations.