: Background: Cigarettes contain Polynuclear Aromatic Hydrogen and nicotine which can interfere with the process of spermatogenesis. The activity of free radicals can be inhibited by isoflavone and the amino acid arginine contained in soybean seeds.Objective: To reveal the histopathological features of the testis of Swiss rats exposed to cigarette smoke and administered with soybean. Method: Experimental research employed nine rats which were divided into three groups. Rats in Group A were fed with standard pellet for 35 days (negative control). Rats in Group B were exposed to cigarette smoke and were fed with standard pellet for 35 days. Rats in Group C were exposed to cigarette smoke and were fed with soybean 5 gr/day for 35 days. Results: Features of tubulus seminiferus with layers of spermatogenic cells which is in accordance with normal developmental stages were revealed in Group A. Meanwhile, in Group B, features of tubulus seminiferus with loose and irregular layers of spermatogenic cells were seen. Tubular lumen contained less spermatocytes and spermatid than Group A, making the lumen looked bigger and filled with less spermatozoa. In Group C, features of tubulus seminiferus with spematogenic cells which were denser than Group B were revealed. Conclusions: Exposure to the smoke of 2 cigarettes/day cause a decrease in the number of spermatogenic cells of the tubulus seminiferus in rat's testis. The administration of soybean of 5 gr/day cause an increase in the number of spermatogenic cells of the tubulus seminiferus in rat's testis exposed to cigarette smoke