An epidemiological study of major mental disorder in a slum area with a population of 100.707 and an adult popualtion of 66.645 in West Jakarta ( Tambora District) was conducted in 1983. The model used was a two stage community survey model. In the first stage a case finding surve was held in which possible patients were screened for futher investigations in the second stage using the Present State Examination (PSE) and other instruments. Diagnosis was made using the Indonesian diagnostic glossary and the ICD 8 classification system. In both stages intruments developed by WHO were used. As research area the Tambora District in West Jakarta, an urban slum area, was chosen. This area was considered appropriate for several reasons. It was an are with one of the highest population density in the country. It was a multi-ethic community with low population mobility and socio-economic level. It was close to a major mental hospital. On the one hand the many field workers were familiar with the area, and on the other hand the local people personally knew many of the field workers, since these workers lived in and around the area. This district could provide a reasonably good demographic data breakdown and goverment as well as health authorities in the region were eager to assist fielt workers in their work. There sub district with a popualtion of more than 100.000 with mutual borders were selected for investigation. In the first stage, case finding was done through key persons and informants. Twelve cases vignettes were read to them describing various psychotic profiles. When necessary, a questionnaire describing psychotic symptoms profiles. When patient were thus identified-called in this project as possible cases, in the second stage psychiatrists visited their houses accompanied by village head men or members of their staf and a psychiatric examination was undertaken using the PSE ass interview schedule. A weekly meeting was held among psychiatriests to discuss problem in the field, recognation of symptoms, and diagnosis. For the final diagnosis a consensus was reached based on the current Indonesian diagnostic glossary and experience of senior psychiatrists. Included in the project were all psychotic patient with active symptoms, epileptics and mental retardates. Those in emission or without manifest symptoms were exluded. The result showed that a total of 145 psychotic were identified in a population of 100.707 individuals giving a prevalence of 1.44 per 1000 population. For age above 15 years for which the population was 66.645 indivuals the prevalence was 2.18 per 1000 population. The prevalance of schizophrenia for adult males was 1.76 and for females 1.04 per 1000 population. For both males and females the prevalence was 1.41 per 1000 population. For other types of psychoses the rates were much lower. Schizophrenia accounted for 65% of all psychoses in the community, which was slightly lower than for admitted patients. For epilepsy a total of 26 epilepsy were indetified. The prevalence for the adult population was 0.32 per 1000 popualtion for males and 0.46 per 1000 population for females. This figure was rather low compared with other surveys becouse case finding was made using key informant in the community and was not based on EEG findings. With regard to mental retardation the methodology was slightly changed, e.g.a. household survey was made for a population of approimately 10.000 subject randomly chosen from the three research areas. A total of 12 subject were identified, giving a prevalence for the adult population of 1.56 per 1000 population for males and 2.22 per 1000 population for females, with an overall prevalence of 1.89 per 1000 population. In addition to prevalence studies a composite profile of Indonesian schizophrenic using the CATEGO Program was constructed. Subsequently, comparisons were made between schizophrenic patients from Indonesian (90 subject as classified using the CATEGO S and P class) and from the Medical Research Council (MRC),Psychiatric Unit, Instutite of Psychiatry, London using the same class. Comparrison between these groups of schizophrenic revealed that the syndrome profile in general was the same. The percentage of syndromes seen more in Indonesian patients were:20 OV (Overactivity),2 CS (Catatonic syndrome),3 IS (Incoherent speech),4 RS (Residual syndrome),and 26 NG (Self-neglect). Syndromes seen less in Indonesian patients were: 14 PE ( Delusions of persecution), 18 VH ( Visual hallucinations), 19 OH (Ollfactory hallucination), 24 ED ( Special feature of depression), 35 OD (Other symptoms of depression), 29 LE (Lock of energy), and 6 SD ( Simple depression). The structuring of schizophrenic symptomatology through culture seemed to be operating also in Indonesian patients.