Here we are reporting a case of Brief psychotic disorder with type I Arnold Chiari malformation and agenesis of carpos callosum which was detected on MRI. The patient was started on antipsychotics and underwent decompression surgery. Patient is on regular follow up and returned to normal daily life within few weeks. Following the surgery the antipsychotics was tapered down and over a period of 9 months the antipsychotics were stopped. Patient is maintaining well in the follow-up. With the usage of improved neuroimaging technique, report of morphological abnormality of brain in psychiatric patients has increased and as authors we suggest that neuroimaging investigation is valuable in psychotic illness .