This study was done in order to correlate the C-Reactive Protein levels (CRP) determined by nephelometric technique, with other infection indicators, and to know its exactness in early detection of chorioamnioitis. Thirty patients were prospectively studied with pregnancies from 28 to 35 weeks of gestation with diagnosis of premature rupture of membranes (PRM); and were compared to control group (30 patients) with similar gestation without PRM, infection, autoimmune diseases or chronic inflammation. The value for CRP was 2 mg/dl. The study group included 17 patients considered as positive, and 13 negative; the differences in CRP values in infected women was significant and not infected ones with a probability less than 0.001 (Fisher), with a sensitivity of 94.12%, and specificity of 100% positive predictive value of 100%, and a negative predictive value of 98.86%. The present data show that CRP is an early detector of amniotic infection.