Introduction: The interface between psychiatric disorders and organicity has been a matter for contentious debate.
Aim: To report an interesting clinical case of moderate homocystinuria presenting with significant psychiatric and neurological deficits.
Method: A case report highlighting the impact of homocystinuria on producing intractable rapid cycling bipolar affective disorder.
Discussion: Homocystinuria is a frequently missed cause for treatment-resistant bipolar affective disorder.
Keywords: bipolar affective disorder; homocystinuria; recurrent strokes.