Antibodies against soluble liver antigen/liver pancreas (anti-SLA/LP) are highly specific for autoimmune hepatitis (AIH) and have been linked with a more severe clinical course of the disease, frequent relapses after treatment withdrawal and worse outcome. To address definitely the clinical significance of anti-SLA/LP, we investigated a large number of anti-SLA/LP-positive and -negative patients followed in three referral centres. Prospectively collected data from 89 anti-SLA/LP-positive AIH patients (29 from Hamburg-Germany, 20 from Bologna-Italy and 40 from Larissa-Greece) were analysed retrospectively. Age- and sex-matched anti-SLA/LP-negative patients served as disease controls (n = 230; 1:2.5 ratio). In respect to baseline characteristics, anti-SLA/LP-positive patients were more frequently asymptomatic compared to anti-SLA/LP-negative (P < .05). However, anti-SLA/LP-positive patients did not differ from anti-SLA/LP-negative in terms of the overall response to treatment, disease progression and survival even though, they were less likely to achieve corticosteroid withdrawal (P < .05), needed longer treatment duration to achieve first complete response (P < .001) and relapsed more frequently after treatment withdrawal compared to anti-SLA/LP-negative patients (P = <.001). We showed that anti-SLA/LP antibodies do not characterize a group of AIH patients with distinct features and cannot identify patients with a more severe form of the disease or worse survival. Most importantly, however, anti-SLA/LP-positive patients appear to require lifelong immunosuppression as they are less likely to achieve the cessation of corticosteroids and present higher relapse rates after treatment withdrawal. Therefore, close long-term monitoring should be advised in all anti-SLA/LP-positive patients after withdrawal of immunosuppressive treatment. © 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.