Munida gregaria is a galatheid very abundant in coastal waters of southern South America playing an important role in the trophic webs of the subantarctic coastal ecosystem. Different reproductive aspects of this species were studied from samples obtained by coastal trawlers between September 1997 and December 2000, which allowed the analysis of a total of 10,868 crabs. The reproductive period started in June, and females with small clutches composed of non-fecundated eggs were found in many cases. The size of clutches increased during the reproductive period, and the simultaneous presence of eggs at different stages of development was observed in the same female. In part of the population, larval hatching started in September, after which females mated again. These embryos hatched between late November and mid-December. Females reached physiological maturity between 9 and 12 mm CL and males between 6 and 8 mm CL. Fecundity was initially low (less than 500 eggs/female), and clutches were completed during the reproductive season, until a maximum of 7545 eggs. During the reproductive season males migrate to shallow waters where they gather for mating.