Mycoplasma hominis and Ureaplasma urealyticum were cultured and counted in the gastric fluid of 153 neonates divided into three groups: 28 preterm neonates managed in an intensive care unit (Group I); 83 full term neonates with suspected infection (Group II); and 42 full term neonates with no evidence of infection (Group III). The colonization rate (17.85 %) in the intensive care unit group was not significantly different from the rates seem in the two other groups. These results do not militate against the pathogenic role of the two organisms studied but rather suggest a contributory role of other factors.