During the previous 34 months, 3 hypertensive patients on long-term thiazide therapy were admitted to the medical department, Mubarak Hospital, Kuwait, with atrial fibrillation (AF) and hypokalaemia. They received potassium chloride by intravenous infusion, followed by oral therapy with reversion to sinus rhythm. There were no clinical, electrocardiographic, radiological, or echocardiographic signs of cardiac or pericardial disease, and the other usual cases of AF were also excluded. The contribution of thiazide-induced hypokalaemia to the occurrence of AF in our patients is discussed.