Tachyarrhythmia following scorpion envenomation might be an indication for anti venin therapy. We present a case of an unusual cardiotoxic response to Leiurus quinquestriatus ('yellow scorpion') venom-second degree atrio-ventricular block (Mobitz type 1). We review the biological activities of L. quinquestriatus' venom and the arrhythmia's possible pathophysiology. The question arising from this case is the therapeutic approach to cardiotoxicity and bradyarrhythmias induced by scorpion envenomation-mainly, the indication for anti serum therapy.