BACKGROUND Schizophreniform disorder remains poorly understood and has been reported probably to be a heterogeneous group of psychotic disorders. METHODS This study compared first-episode schizophreniform disorder (N=12) and schizophrenia (N=18) patients. The authors propose that schizophreniform disorder has a different type of onset and outcome than schizophrenia. Patients were given extensive assessments at initial evaluation, 6 month follow-up, and 24 month follow-up. Comparisons between the two groups were made on type of onset, demographic, clinical ratings and outcome variables. RESULTS Patients with schizophreniform disorder compared to patients with schizophrenia were more likely to have an acute onset (P=0.003), and have recovered by 6 months (P=0.03). However, there were no differences in outcome at 24 months. Furthermore, all schizophreniform cases except for two were re-diagnosed at 24 months as having schizophrenia. CONCLUSIONS The findings suggest that the initial differences of schizophreniform disorder compared to schizophrenia were not apparent at 24 months follow-up. Schizophreniform disorder did not emerge as a highly distinctive and stable form of psychosis that merits a diagnostic classification separate from schizophrenia.