Although the echinoderms have been the subject of various investigations by many authors, those of the Red Sea species till now; have received little attention. Sea cucumbers (Holothuroidea) are marine animals that present in the group of echinoderms. They are distributed from the shore to the greatest depths. The importance of detailed reproductive biological studies on Holothuria atra are necessary due to its important role in the conservation of the marine environment. Samples of the present study was collected from three sites at north Hurghada City, Red Sea during the period from January to December 2003. Four maturity stages were assigned for each sex as immature, maturing, ripe and spent stages. From the monthly and size distribution of these maturity stages of both sexes, it was found that the ripe stage was observed most time of the year for Holothuria atra with high abundance in June and November for males and from June to December for females. The observed size at first sexual maturity was found at 16.5 cm and 15.5 cm total length for males and females, whereas the calculated size was 16.5 cm for females and 17.5 cm for males respectively. The maximum observed oocyte diameter was observed during the intensive period of spawning season for Holothuria atra being in the range from 175 to 200 (µm). Fecundity of Holothuria atra was found to be in the range from 12110 to 1342278 oocytes for individuals of size range from 21.0 to 25.0 cm total length. The relation between absolute fecundity and gonad weight is best fitted by a linear regression.