A representative sample of schizophrenic subjects was collected for epidemiological and clinical follow-up in 1972 from the pool of 8069 patients registered in the Croatian Psychotics Case Register (CPCR). This sample comprised 402 patients (207 males and 195 females), who were followed up until 1990/91. The diagnosis of schizophrenia, catatonic type according to ICD-8 (V/295.2), was made in 59 cases (14.7%; 28 males, 31 females) at least once in the course of the follow-up. This study presents data concerning the diagnostic instability of the catatonic subtype during the long-term follow-up. As subtype diagnoses were frequently changed over the course of illness, at the end of the follow-up, the diagnosis of catatonic schizophrenia was only confirmed in 11 (18.6%) cases. Positive family history of psychosis was found in 44.1% of catatonic patients, a percent significantly greater than the corresponding figure for all non-catatonic schizophrenic subtypes combined (20.1%). This study provides preliminary evidence that the catatonic subtype of schizophrenia is a separate diagnostic entity with a high familial loading.