The purpose of this study was to determine whether amniotic fluid glucose concentrations is of value in the rapid diagnosis of intraamniotic infection. Amniocenteses were performed in 168 patients with preterm labor and intact membranes. Amniotic fluid was cultured for aerobic and anaerobic bacteria, as well as Mycoplasma species. The prevalence of positive amniotic fluid cultures was 13.6% (23/168). Patients with positive amniotic fluid cultures for microorganisms had significantly lower median amniotic fluid glucose concentrations than patients with negative amniotic fluid cultures (median 11 mg/dl, range 2 to 30 mg/dl vs median 28 mg/dl, range 3 to 74, respectively; p less than 0.001). Amniotic fluid glucose concentrations below 14 mg/dl had a sensitivity of 86.9% (20/23), a specificity of 91.7% (133/145), a positive predictive value of 62.5% (20/32), and a negative predictive value of 97.8% (133/136) in the detection of a positive amniotic fluid culture. Amniotic fluid glucose determination is a rapid, sensitive, inexpensive, and simple test for the detection of intraamniotic infection in women with preterm labor and intact membranes.