OBJECTIVE: To study the correlation of erythrocyte immune function between normal neonates and their mothers and the influence of various obstetric factors on neonatal erythrocyte immune function. METHODS The adherent rate of complement 3b-receptor on the surface of red blood cells (RBC-C3bRR) and the immune complex adherent rate of red blood cells (RBC-ICR) were detected using the erythrocyte saccharomyces rosette test in 104 normal neonates and their mothers. The correlation of erythrocyte immune function between neonates and their mothers was evaluated by the maternal-infant paired test. RESULTS: The levels of RBC-C3bRR (16.80±1.56% vs 16.23±1.63%; P<0.05) and RBC-ICR (5.72±1.63% vs 5.02±1.38%; P<0.01)) in neonates were significantly higher than those in their mothers. There was a significantly positive correlation in RBC-ICR levels between neonates and their mothers (r = 0.28, P<0.05). No correlation was found in RBC-C3bRR levels between the two groups. Neither RBC-C3bRR nor RBC-ICR levels of neonates were associated with various obstetric factors such as amniotic fluid, placenta, umbilical cord, parturient patterns, and puerpera anemia and pregnancy-induced hypertension syndrome. CONCLUSIONS: The erythrocyte immune function in neonates has a relatively mature level and correlates with their mothers' erythrocyte immune function. Various obstetric factors have no influences on neonatal erythrocyte immune function.［Chin J Contemp Pediatr, 2007, 9 (1):19-21］