The reproductive cycle of the clam; Donax trunculus Linnaeus, 1758, from New Damietta shore,was investigated during the period from May 2008 to July 2009. Reproductive maturity was estimated by the assessment of gonad index and microscopic examination of gonadal smears and sections. Six distinguishable gonad stages based on histological examination were determined in male and female clams. Both sexes showed synchronism in gonads development and spawning. The gametogenesis began in late autumn and ended in late spring. An annual pawning phase was recorded during the period from May to September. D. trunculus is a dioecious species without sexual dimorphism or sex reversals.  The ratio of males (M) to females (F) (1.0 M: 0.76 F) was significantly different from the expected ratio of 1:1 (X² = 12.27, P < 0.0005). This finding indicates a greater number of males than females. The present work indicated that D. trunculus is well adapted to the specific environmental conditions of New Damiettashore in order to maximize its reproductive success.