BACKGROUND: Concurrent extrahepatic autoimmune disease (CEHAID) associated with autoimmune hepatitis (AIH) have been incorporated into the diagnostic criteria stipulated by the International Autoimmune Hepatitis Group (IAIHG). Large comprehensive cohort data on the extrahepatic autoimmunity in AIH remain scanty. AIM: To systematically assess features and clinical impact of CEHAID on AIH. METHODS: Clinical records of 562 patients with AIH from two tertiary centres in the UK were retrospectively reviewed. RESULTS: Prevalence of CEHAID in patients with AIH was 42%. Autoimmune thyroid disease was the commonest CEHAID associated with AIH (101/562, 18%). Autoimmune skin diseases were more prevalent in AIH-2 than AIH-1 (21.9% vs 7%, P=.009). Personal history of CEHAID was more commonly found in AIH patients with than without first-degree family history of CEHAID [48/86 (55.8%) vs 169/446 (37.9%), P=.002]. AIH patients with CEHAID were more often women (85.2% vs 76.1%, P=.008), had higher post-treatment IAIHG score (22 vs 20, P<.001), less reactivity to smooth muscle antibodies (49.8% vs 65%, P<.001), more likely to have mild fibrosis at diagnosis (20.9% vs 6.5%, P<.001) and less often had ascites (6.3% vs 13.6%, P=.008) and coagulopathy (1.18 vs 1.27, P=.013) at presentation. Presence of CEHAID, however, did not significantly affect disease progression, prognosis and survival in AIH. CONCLUSIONS: Our study confirms the strong association of CEHAID with AIH. Association between personal and familial extrahepatic autoimmunity especially among first-degree relatives was evident. Presence of CEHAID may influence clinical phenotype of AIH at presentation, but without notable impact on the long-term clinical outcomes.