Objective: There has been a trend of prescribing new second generation antipsychotics (SGAs) as a first-line treatment for psychosis in many developed countries. However, there has been very few studies concerning this topic in a developing country such as Thailand. This study examined the pattern of prescribing antipsychotic drugs by Thai psychiatrists in a tertiary hospital. Methods: Active clinical psychiatric outpatient files (n=1750) between January and March 2003 from Songklanagarind Hospital, a tertiary university hospital in southern Thailand, were retrospectively reviewed. Results: Most patient (82.9%) who were prescribed an antipsychotic received only one oral medication. Among patients with schizophrenia and schizoaffective disorder, the majority (67.9%) received a first generation antipsychotic (FGA). Fewer patients were prescribed a SGA alone (13.1%) or a depot preparation alone (6.4%). Of those patients on a SGA, the most commonly prescribed drugs were a generic form of clozapine (64/.7%), risperidone (19.6%) and olanzapine (15.7%). For patients on a FGA, the most commonly prescribed medications were perphenazine (52.8%) and chlorpromazine, CPZ (19.7%). The mean dose was significantly higher for males (209.14 ±197.49 mg/d of CPZ equivalent) than females (158.57±163.45 mg/d) (t=3.61, p <.001). Conclusion: SGAs are not yet widely prescribed in our hospital perhaps due to the high drug cost and the availability of medication. Thai patients may respond to a lower dosage compared to dosages reported in Western studies. Further systematic research is needed before conclusions on this topic can be drawn.