Objective:People with psychiatric diseases have a severely increased risk for physical morbidity and premature death from physical diseases. The aims of the study were to investigate the occurrence of cardiovascular diseases (CVD), diabetes (DM) and obesity in schizophrenia and depression in three different geographical areas - Asia (Japan), Africa (Nigeria) and Western Europe (Switzerland, Germany and Denmark) - and to search for possible transcultural differences in these correlations, which would also reflect the differences between low-income areas in Africa (Nigeria) and high-income areas in Europe and Japan.Method:Patients with International Classification of Diseases (ICD-10) F2 diseases (schizophrenia spectrum disorders) and F3 diseases (affective disorders) admitted to one Nigerian, one Japanese, two Swiss, two German and six Danish centres during 1 year were included. Physical diseases in accordance with ICD-10 were also registered. Psychiatric and physical comorbidity were calculated and standardized rate ratio incidences of background populations were our primary measures.Results:Incidence rate ratios were increased for both CVD, DM and overweight in both F2 and F3 in all cultures (Western Europe, Nigeria and Japan) within the same ranges (however, the Japanese results should be interpreted conservatively owing to the limited sample size). Overweight among the mentally ill were marked in Nigeria. A parallelism of the incidence of overweight, CVD and diabetes with the occurrence in background populations was seen and was most marked in overweight.Conclusions:Overweight, CVD and DM were increased in schizophrenia spectrum disorders and affective disorders in all three cultures investigated (Western Europe, Nigeria and Japan). Lifestyle diseases were also seen in Nigeria and Japan. The results from this study indicate that cultural background might be seen as an important factor in dealing with lifestyle diseases among people with a severe mental illness, as it is in the general population.