We present a case of complete atrioventricular (AV) block following slow pathway ablation for atrioventricular nodal reentrant tachycardia (AVNRT) treated only by colchicine administration. The patient’s electrocardiogram showed complete AV-block at two weeks after catheter ablation. Colchicine is effective for late-onset AV-block caused by catheter ablation for AVNRT.