Nile tilapia, (Oreochromis niloticus) is an important species for freshwater aquaculture and considered to be one of the most important warm-water cultured fish species in the world. This study was conducted to determine the side effect of Sulphatrim® and Amoxi-vet® on fertility in Nile tilapia fish, a total number of 90 fish were divided into 3 equal groups (each of 30 fish). Then each group divided equally to A and B subgroups. Sera , milt and tissue samples were collected. Milt picture (sperm count, motility and vitality % ) were determined as well as some reproductive hormones ( estrogen , progesterone and testosterone ) were measured. As well as the effect of these drugs on the histopathological picture of the sex organs (testes and ovaries ) of the treated fish was determined .It was concluded that Sulphatrim has non significant effect on the milt picture and on the tested reproductive hormone in male and female Nile tilapia fish. However Amoxi-vet caused a significant decrease in sperm count as well as sperm motility and vitality .Moreover the drugs induced a significant decrease in the tested reproductive hormones that was confirmed by the histopathological picture of the examined sex organs.