AIM To evaluate the therapeutic effects of ursodeoxycholic acid(UDCA) on autoimmune hepatitis(AIH).METHODS A total 136 patients who were diagnosed with AIH were included in our study. All of the patients underwent a liver biopsy, and had at least a probable diagnosis on the basis of either the revised scoring system or the simplified scores. Initial treatment included UDCA monotherapy(Group U, n = 48) and prednisolone(PSL) monotherapy(Group P, n = 88). Group U was further classified into two subgroups according to the effect of UDCA: Patients who had achieved remission induction with UDCA monotherapy and showed no sign of relapse(Subgroup U1, n = 34) and patients who additionally received PSL during follow-up(Subgroup U2, n = 14). We compared the clinical and histological findings between each groups, and investigated factorscontributing to the response to UDCA monotherapy.RESULTS In Group U, 34 patients(71%) achieved and maintained remission over 49(range: 8-90) mo(Subgroup U1) and 14 patients(29%) additionally received PSL(Subgroup U2) during follow-up. Two patients in Subgroup U2 achieved remission induction once but additionally required PSL administration because of relapse(15 and 35 mo after the start of treatment). The remaining 12 patients in Subgroup U2 failed to achieve remission induction during follow-up, and PSL was added during 7(range: 2-18) mo. Compared with Subgroup U2, Subgroup U1 had significantly lower alanine aminotransferase(ALT) levels at onset(124 IU/L vs 262 IU/L, P = 0.023) and a significantly higher proportion of patients with mild inflammation(A1) on histological examination(70.6% vs 35.7%, P = 0.025). When multivariate analysis was performed to identify factors contributing to the response to UDCA monotherapy, only a serum ALT level of 200 IU/L or lower was found to be associated with a significant difference(P = 0.013).CONCLUSION To prevent adverse events related to corticosteroids, UDCA monotherapy for AIH needs to be considered in patients with a serum ALT level of 200 IU/L or lower. AIM To evaluate the therapeutic effects of ursodeoxycholic acid (UDCA) on autoimmune hepatitis (AIH). METHODS A total 136 patients who were diagnosed with AIH were included in our study. All of the patients underwent a liver biopsy, and had at least a probable Initial treatment included UDCA monotherapy (Group U, n = 48) and prednisolone (PSL) monotherapy (Group P, n = 88). Group U was further classified into two subgroups according to the effect of UDCA: Patients who had achieved remission induction with UDCA monotherapy and showed no sign of relapse (Subgroup U1, n = 34) and patients who later received PSL during follow-up (Subgroup U2, n = 14). We compared the clinical and histological findings between each groups, and investigated factors contributing to the response to UDCA monotherapy. RESULTS In Group U, 34 patients (71%) achieved and maintained remission over 49 (range: 8-90) mo (Subgroup U1) and 14 The remaining 12 patients (29%) received additional PSL (Subgroup U2) during follow-up. Two patients in Subgroup U2 achieved remission induction once but additionally required PSL administration because of relapse (15 and 35 months after the start of treatment). Compared with Subgroup U2, Subgroup U1 had significantly lower lower alanine aminotransferase (ALT) levels at onset (124 IU / kg) in Subgroup U2 failed to achieve remission induction during follow-up, and PSL was added during 7 L vs 262 IU / L, P = 0.023) and a significantly higher proportion of patients with mild inflammation (A1) on histological examination (70.6% vs 35.7%, P = 0.025). When multivariate analysis was performed to identify factors contributing to the response to UDCA monotherapy, only a serum ALT level of 200 IU / L or lower was found to be associated with a significant difference (P = 0.013) .CONCLUSION To prevent adverse events related to corticosteroids, UDCA monotherapy for AIH needs to be considered in patients with a serum ALT level of 200 IU / L or lower.