Amniotic fluid samples from 95 internally monitored patients were examined to determine whether the appearance of polymorphonuclear leukocytes [PMN] or bacteria could predict intrauterine infection. All patients delivered vaginally. More than 1 PMN/oil field were seen in specimens of 32% of patients; bacteria were seen in specimens of 52% of patients, and organisms were grown in 93% of specimens, yet, the overall maternal infection rate was only 6.3%. Infection developed in only 10% of patients with PMN in the fluid and 6% of patients with positive gram strain or cultures. For patients who deliver vaginally, the appearance of PMN or bacteria does not predict infection.