The objective of this study was to determine the value of interleukin-6 (IL-6) in cervical secretion to diagnose microbial invasion of the amniotic cavity in patients with premature rupture of the membranes. Cervical secretions were sampled immediately before amniocentesis in 124 patients with singleton pregnancies and preterm premature rupture of the membranes. Gestational age ranged between 24 and 32 weeks. Amniotic fluid was cultured and IL-6 measured in amniotic fluid and cervical secretions. A total of 33.8% (21/124) of the amniotic fluid cultures had positive results. In cervical secretions the median concentration of IL-6 was 672 pg/ml (range 5–1,250) in the presence of intra-amniotic infection in contrast to 95.5 pg/ml (range 12–640) in women with negative amniotic fluid culture (p ≤0.001). There were no differences between IL-6 concentrations in the cervical secretions of patients with or without obvious leakage of amniotic fluid. A significant relationship was found between IL-6 levels in amniotic fluid and in cervical secretions (ρ = 0.74, p ≤0.001). An IL-6 level in cervical secretions >200 pg/ml had a sensitivity of 78.5%, a specificity of 73.1% and a relative risk of 4.6 for intra-amniotic infection. Receiver-operator characteristics curve analysis showed that IL-6 assay in cervical secretions is comparable to IL-6 assay in amniotic fluid in predicting intra-amniotic infection (p = 0.468).In conclusion, intra-amniotic infection is associated with increased levels of IL-6 and concentrations in cervical secretions are related to amniotic levels. The measurement of IL-6 in cervical secretions may help to noninvasively identify intra-amniotic infection among pregnancies with preterm premature rupture of membranes.