BACKGROUND: There are few mental health data for Somali people. This is due to the absence of culturally validated appropriate assessment instruments and methodological challenges. We aimed to develop a culturally appropriate Soc Psychiatry Psychiatr Epidemiol. 2006 May;41(5):400-8. Epub 2006 Mar 6 instrument, and address the methodological challenges and assess some risk factors for mental disorder among Somalis in London. METHODS: Following a comprehensive process of cultural adaptation of the MINI Neuropsychiatric Interview, we assessed ICD-10 mental disorders among 143 Somalis recruited from GP registers and community sites. Associations with demographic and economic characteristics, sampling venues, cultural and migration related risk factors are reported. RESULTS: A higher risk of mental disorders was found among Somalis who used Khat (OR = 10.5, 1.1-98.3) claimed asylum at entry to the UK (OR = 12.8, 2-81.4) and recruits from primary care rather than from community sites (OR = 5.9, 1.4-25.8). A lower risk of mental disorders was found amongst Somalis in employment (OR = 0.03, 0.01-0.61), and those receiving education in the UK and in Somalia (OR = 0.13, 0.02-0.92). Over a third of subjects had any mental disorder (36.4%, 28.4-44.4), mainly common mental disorders (CMD) (33.8%, 26-41.5) and post-traumatic stress disorder (PTSD) (14%, 8.8-20.8). CMD were found among 80% of those with PTSD. CONCLUSION: Public health interventions for Somalis should focus on CMD as well as PTSD, khat use and mental health screening for suicide risk and mental disorders on arrival.