This study aims to establish the isolation frequency of species of the family Enterobacteriaceae in fecal samples of South American common sea lion (Otaria flavescens). Thirty fecal samples were collected from the resting ground of an urban sea lions colony in Valdivia, southern Chile. The bacteria species and their isolation frequencies were Edwarsiella tarda (73%), Escherichia coli (70%), Hafnia alvei (33%), Morganella morganii (7%), Proteus mirabilis (7%), Klebsiella pnuemoniae subsp. pneumoniae (3%), Serratia rubidea (3%), Providencia rustigianii (3%) and Citrobacter braakii (3%).