Objective To explore changes of the immune function of red blood cells in gastric disease.Methods RBC C3b receptor rosette(RBCC3bRR)and RBC immune complex rosette(RBCICR)were tested in chronic gastritis group(n =103),duodenal ball ulcer group(n =75)and control group(n =30)to evaluate the immune function of RBC.Results RBCC3bRR were(20.83 ± 5.16)％ in the control group,(16.26 ±5.17)％ in the chronic gastritis group and(13.65 ± 5.19)％ in the duodenal ball ulcer group.RBCICR were respectively(7.63 ± 4.09)％,(10.59 + 4.45)％ and(10.04 ± 4.13)％ in these three groups.RBCC3bRR of chronic gastritis and duodenal ball ulcer were lower than control group(P ＜0.0l),while RBCICR were higher than normal control group(P ＜0.05 and P ＜0.01 respectively).There was no significant difference on RBCC3bRR and RBCICR between HP negative chronic gastritis and HP negative duodenal ball ulcer and between HP positive chronic gastritis and HP positive duodenal ball ulcer(P ＞ 0.05).RBCC3bRR of HP positive chronic gastritis and duodenal ball ulcer was significantly lower than that of HP negative(P ＜ 0.05and P ＜ 0.01 respectively),RBCICR significantly higher than that of HP negative(P ＜ 0.01).After HP eradication,RBCC3bRR of patients with chronic gastritis and duodenal ball ulcer was increased significantly (P＜0.05 and P ＜ 0.01 respectively).RBCICR was significantly lower than before treatment(P ＜ 0.01).Conclusion HP infection,chronic gastritis and duodenal ulcer can decrease the immune function of red blood cells.