Introduction: Electrification in developed countries has progressively increased the mean level electromagnetic fields to which populations are exposed. These human made fields are substantially above the naturally occurring ambient electric and magnetic fields. The studies have been indicating EMF induced effects on biological systems. Methods: This study is carried out to measure the changes in testosterone hormone level and changes in testes tissue on 36 adult male Guinea PIGs that divided to 6 groups. Group A as control group exposed to nil electromagnetic field for two hours per day for 5 days duration, group B exposed to 0.013 µT in 5 Hz to the Same duration period, group C exposed to 0.207 µT in 50 Hz in similar conditions, group D exposed for four hours per day for 5 days in 0.013 µT, group E tested in 0.207 µT as group D, group F used as controlled group exposed for four hours per day in nil electromagnetic field. Guinea PIG blood was tested after 5 days.Results: The results indicated testosterone level decreased (p£0.001); also testes tissues were sampled and observed main tissue changes in some treatments.Conclusion: EMF in groups B and D cause to damage leydig cells and increase the inter-tissual space because of increasing intra- tissual liquid and emerging edema that probably arise from testes tissue cells damage . Because of leydig cells damage the level of testosterone hormone in blood decreased and led to disorder in spermatogen.