Solen dactylus is a razor clam distributed throughout the coast of the northern Persian Gulf. Study on biology of razor clams in this area is important for an essential management where these clams are overfished without any control. This study provides the first estimate of growth rate and an interpretation of the reproductive cycle of S. dactylus on the coast of the Persian Gulf (Bandar Abbas). In this study, 945 razor clams were collected from April 2007 to March 2008 along two transects of Golshahr coast in Bandar Abbas. Von Bertalanffy growth parameters for transects 1 and 2 ranged from 101–108 mm for asymptotic length (L∞), 0.27–0.28 year−1 for growth constant (k), and −0.99–0.94 for age at length zero (t0), respectively. Gonads were stained with haematoxylin and eosin and gametogenic stages were based on seven stages: (Stage 0) sexual rest; (Stage I) proliferation of gonad and start of gametogenesis; (Stage II) advanced gametogenesis; (Stage IIIA) ripeness; (Stage IIIB) start of spawning; (Stage IIIC) restoration; and (Stage IV) emission. The result showed that S. dactylus is a gonochoric clam and both males and females demonstrated synchronism in gonadal development. The gametogenic cycle began in late August and ended in late February. After several minor spawnings, plus a major one in January, the razor clams entered to the sexual rest stage in March.