The presence of Yersinis enterocolitica was investigated in feces of 1,300 children younger than 5 years, hospitalized because of presenting acute diarrheic disease in Cuba during 1985-1988 period at different provincial pediatric hospital, as well as in Havana City. Selective agar base for Yersinia was used supplemented with cephsuloidin, Irgasan and novoviocin (CIN) and buffered saline solution as enrichment medium. This last one at 4 degrees C during 21 days with weekly resowings to the selective medium. Isolation of Yersinia enterocolitica was not obtained in any of the patients under study.