Objective To compare the effects of different methods of anesthesia on immune function during renal transplantation. Methods Thirty-nine uremic patients of both sexes (20 male, 19 female) aged 19-65 yr, undergoing renal transplantation were studied. Patients who had infection, fever, immune system disease or had received immunoregulatory drugs were excluded. The patients were randomly divided into 3 equal groups: Ⅰ continuous epidural anesthesia group (CEA , n = 13); Ⅱ combined spinal-epidural anesthesia group (CSEA, n = 13) and Ⅲ general anesthesia group (GA , n = 13). In group I an epidural catheter was inserted at T12-L1 or L1-2 into epidural space and advanced in cephalad direction and a mixture of 2% lidocaine and 0.7% dicaine (1: 1) 11-12 ml was given. The height of block was T8 In group II CSEA was performed at L2-3 and a mixture of 1% dicaine, 10% glucose and 3% ephedrine (1 : 1 : 1) 3 ml was injected intrathecally. An epidural catheter was threaded in a cephalad direction. The block height was T8. 2 % lidocaine was given epidurally when the operation lasted more than 2 hours. In both group I and II pathidine 50 mg and droperidol 5 mg were given iv. In group III anesthesia was induced with fentanyl 5 ?g kg-1 , etomidate 0.3 mg ? kg-1 and vecuronium 0.08 mg ? kg-1 and maintained with isoflurane supplemented with intermittent iv boluses of vecuronium. Blood samples were obtained from peripheral vein for determination of CD+3 , CD+4 , CD+8 , CD+4 /CD+8 ratio and IgG, IgA, IgM, C3 , C4 before anesthesia (T0 ) , after anesthesia (T1), before blood transfusion (T2), 30 min and 1 h after blood transfusion (T3,4) ,when renal circulation was restored (T5), at the end of operation (T6 ) and 1 and 3 days after operation (T7.8) .Results There were no significant changes in T lymphocyte subgroups, immunoglobulins and complements measured after anesthesia (T1 ) as compared with the baseline values(T0) in the 3 groups. In group Ⅰ and Ⅱ CD+3 , CD+4 , IgG, IgA, IgM, C3 , C4 and CD+8 unchanged significantly as compared with the baseline values (T0 ) ; CD+4 /CD+8 ratio decreased after anesthesia ( P