Objective To explore the effect and mechanism of early using specific immune RNA (iRNA) for preventing burn infection.Method 129 patients with serious burn were randomly divided into two groups by double blind method. The control group (n=64) was treated with routine method; The therapeutic group(n= 65) was given specific iRNA in addition to the routine therapy. The incidence of infection in two groups were investigated; Meantime, with the methods of monoclonal antibody (McAb) APAAP, 3H- TdR incorporation and MTT colorimetery, the various immune functions of patients were determined. Result (1) the incidences of wound infection and bacteriemia after burn in the therapeutic group were markedly lower than those of the control group; (2) the therapeutic group was also superior to the control group in the general condition and time of the wound healing; (3) on the l0th day postburn, the various immune founction tested in the therapeutio group have approximately restored to the normal levels, while those in the control group were still in low levels. The difference between the two groups was statistically significant (P＜0.01). Conclusion Specific iRNA, which, when used early after burn, can reduce the incidence of postburn infection, and improve immune functions of burned patients.