The DSM-III diagnostic criteria for schizophreniform disorder, mainly based on duration of symptoms, are insufficient to furnish a good treatment strategy. In recent literature, schizophreniform disorder has been grouped either with the schizophrenias or with the affective disorders. Scandinavian researchers have described two other groups of psychotic disorders that resemble schizophreniform disorder. These are the reactive psychosis and the cycloid psychosis. They were found to be different from the schizophrenias and the affective disorders. "Good prognosis" schizophrenia, which has been extensively studied and reported in the literature, is clinically very similar to schizophreniform disorder. The relatively consistent data collected in patients with good prognosis schizophrenia may provide the basis for the additional diagnostic criteria needed in DSM-III schizophreniform disorder.