Early detection of infection is of utmost importance during the conservative management of premature rupture of the membranes (PROM). Sensitivities of C-reactive protein (CRP) and acute-phase proteins (APP) in predicting the infection induced by PROM were studied. The results showed that CRP could demonstrate clinical or subclinical infection with a sensitivity of 100% and 86.7% respectively, and no false positivity was observed. CRP increased remarkably at least 24 hours earlier than that of other parameters when infection occurred. On the other hand the sensitivity of APP (64.1%) was lower with false positivity. Thus, CRP may be used in clinical practice to predict infection resulted from PROM during conservative management.