7d respectively. The time of micturition and voided volume were recorded .The residual urine volume was detected by bladder volume instrument (Bladder Scan BVI-2500). The plasma and urine osmolarity were measured by FM-6 pattern freezing point osmometer. Results: (1) There was significantly difference (P<0.05) of daynight voided volume��voided frequency between A group and those of B,C groups. (2) Bladder emptying rate , maxium bladder capacity (MBC) and plasma urine osmolarity of A, B and C groups were 80��0.07, 0.82 ��0.09, 0.79��0.10; 56��6, 65��14, 61��15 (ml)��285��5, 287��7, 286��8 (mOsm/L)��202��59, 185��65, 216��92 (mOsm/L) respectively and there were no significantly difference among three groups. �� Used the multiple stepwise regression methods to estabilish the best regression equation for predicting the MBC, MBC = 42+0.17*X (ml), X= eight hours (10Am~ 6Pm) voided volume, F=15.561 (P<0.001). Conclusions: The normal newborn��s bladder was stable and emptied almost completely. There is no difference for the renal concentration function of neonate between day and night. " v:shapes="_x0000_s1026">1041