A 14 years male presented with fever and migratory polyarthritis. Investigations revealed second degree AV block of Mobitz type 1 on ECG, leucocytosis, normal ESR, ASO titer and echocardiography. ASO titer repeated on 4 th day of admission was high. A diagnosis of acute rheumatic fever was established by using World Health Organization criteria. The second degree Atrioventricular (AV) block reverted back to normal sinus rhythm on day nine. In developing nations where acute rheumatic fever remains endemic second degree AV block of Mobitz type 1 in teenagers should prompt to the diagnosis of acute rheumatic fever even if supporting evidence of streptococcal infection is absent initially.