The cycle of reproduction of Strombus gigas of San Pedro, Belize was established from January to December 2008 at San Pedro, Belize. All the samplings were carried out by at 10 - 15 m of depth. Not all the conchs sampled had a lip thickness of ?6 mm. The samplings during the fishing ban were carried out with a special authorization of the administration of fisheries of Belize. This study showed a long period of undifferentiated stage. Two gametogenesis periods were observed (January-April and September-December). Mature stage was not observed. Three peaks of spawn and postspawn were observed (February, June and August). Reproductive cycle was compared with occurrence of Apicomplexa parasite and variation of temperature.