++Clinico-genealogical and structural-dynamic analyses were made of endogenous psychoses, paranoid in structure under conditions of their accumulation in an isolated population. Study of 3 generations (forefathers, parents, sibs) in 55 families has demonstrated a high level of psychic morbidity among them: schizophrenia (58.1%), epilepsy (24.3%), oligophrenia (8.3%). The combination of schizophrenia and epilepsy was established in 6.3% of cases. It is assumed that the familial forms of psychoses in isolates are inherited by the polygenous autosomal and recessive type.