One of the most common molluscan species in Egyptian water is Coralliophila violacea (Coralliophilidae, Gastropoda, Mollusca). There are very few studies had been carried out on this species and its importance and its effect on coral reefs in the Red Sea. Reproductive studies of C. violacea indicated that females produce a number of egg sacs, each sac contains a large number of eggs ranged from 222 to 2893 eggs /sac with an overall average of 1046.33 ± 468.9 eggs /sac. The color of the examined egg masses varied from transparent creamy white to light orange and finally to light brown color. The close examination of the colored sacs indicated that the developmental stage of the eggs is the factor behind the differences in color. Male gonad development comprised the spermatogonia, primary (PSC) and secondary spermatocytes (SSC), spermatids and sperm cells (SP) were also examined and measured. The diameter of the spermatogonia of C. violacea varied between 4 and 6 µm with an average of 4.9+0.37 µm.