Abstract: The present study investigated seasonal changes in gonad development and proximate compositions of the mangrove snail, Cerithidea obtusa in the mangrove forest of Ca Mau province, Mekong Delta of Vietnam. Our findings showed that gametogenesis of C. obtusa occurred year around, however, the major spawning period lasted from September to November. The highest spawning synchrony was observed in November with 43% collected individuals in spawning stage. The results also showed that in mangrove snails, proteins are the major component (~60%) followed by carbohydrates (~25%) and then lipids (~5%).