Black-Caribbean patients are more often admitted compulsorily to psychiatric wards than patients from other ethnic groups. We tested the hypothesis that perceived ethnicity of a patient had no independent effect on the risk of compulsory admission. For all consecutive admissions over a 6-month period to acute psychiatric wards in Nottingham, medical officers responsible for the decision to admit completed a questionnaire recording clinical details of the patients and reasons for admission. The results showed that 43.2% of Black-Caribbean patients and 18.8% of White patients were admitted compulsorily (unadjusted odds ratio 3.29, 95% CI 1.71-6.33). Perceived ethnicity (Black-Caribbean) was significantly associated with being young, receiving a diagnosis of psychosis, and being perceived to be at a risk of violent acting out. A forced entry logistic regression model was used to adjust for hypothesised confounding variables such as age, sex, diagnosis, risk, socio-economic status and level of social support. A diagnosis of psychosis, risk of committing violence and being Black-Caribbean had independent effects on the risk of being compulsorily detained. The odds ratio for compulsory detention of Black-Caribbean patients was 2.16 (95% CI 1.03-4.52) after adjusting for the hypothesised confounding variables.