Morphological and histological studies demonstrated that salinity affects gonadal development of Diplodus vulgaris* Fishes exposed to salinity 25%o were characterized by reduction in the gonad size, GSI values and the testes seemed to be atrophied. Degeneration of both spermatogoma and oocytes were observed at this level of salinity. At 16 %o salinity, the gonads were slightly reduced in size, early ripening of males and early sex reversal were observed. By increasing salinity to 4Q%o, the gonad weight and GSI values were decreased. Inhibition of spermatogenesis in males, collapse of the oocytes and marked shrinkag in the nucleus diameter were detected. The ovaries of females showed some types of abnormalities: development of small vacuoles all over the cytoplasm which was not homogenous. It was observed that exposure to salinity 48%o caused the most deleterious effect on the gonads. Hypertrophy followed by degeneration of spermatogonia and deformation of seminiferous lobules, cessation of cell division and deformation of the oocytes were observed.