Out of 60 patients of transient atrial fibrillation including a case followed up for 12 years, 51 cases with unknown etiology or due to ischemic heart disease were studied in this paper. 1. Transient atrial fibrillation tends to induce cerebrovascular accidents although no direct relationship between the two was detected. 2. Transient atrial fibrillation combines frequently with sick sinus syndrome, especially with sinus bradycardia. 3. The cases combined with sick sinus syndrome have not only cardiac problems but also a higher risk of cerebrovascular accidents. 4. At the onset of atrial fibrillation, many cases complain of pollakisuria as well as other symptoms reported previously. 5. No apparent causes for atrial fibrillation was found in more than half of our cases. However, most cases had something to do with physical and/or mental stress.