Cyclical menstrual psychosis is an uncommon, generally a self-limiting mental illness that occurs only in females. It is associated with other menstruation-related disorders and stressful psychogenic factors. Nonetheless, many cases remain unrecognized due to poor awareness of its presence. A young female who presented with psychotic and mood symptoms during each cycle of menstruation was admitted to the psychiatric inpatient unit. There was severe disruption in her activities of daily living and socio-occupational functioning. Treatment involved bio-psycho-social approach in collaboration with Ob-Gyn team with symptoms responding well to a combination of valproic acid and risperidone. Severe affective instability with evident psychosis during menstrual cycle should be evaluated for cyclical menstrual psychosis.