The red crab Ucides occidentalis is a this organism has commercial value and constitutes Golfo de Guayaquil. However, we know few facts about the natural populations and the genetic riches of this specie. For this reason in this research determination of genetic variability of U. occidentalis. this investigation: Recinto 6 de Julio, Reserva Ecológica Manglares Churute y Rese Manglares El Salado. In each zone were collected 20 individuals. Based on the molecular marker