This study was aimed to determine the effect of cadmium on testicles and kidney structure of Oreochromis niloticus in different salinity. Twenty-seven Oreochromis niloticus at age of 5±0.5 months with average size 11±1 cm and average weight 250±50 g were used and divided into nine treatment groups with variations in salinity (0, 5 and 10 ‰) and cadmium levels (0, 2.5, and 5 ppm). After two weeks of treatment periods, testicles and kidney was collected and then processed into histological slide. Result showed that cadmium and salinity variations caused change in diameter of seminiferous tubules in the testicles. Kidney structure also showing various damage such as necrosis and inflammation from groups treated with various concentration of salinity and cadmium. Smallest diameter of seminiferous tubules of the testicles and the highest percentage necrosis and inflammation of kidney was found from salinity:cadmium = 0‰: 5 ppm treatment.