Marijuana is one of the most popular drugs legally admitted for general sale in many countries. To consider it safe and unlikely to develop drug dependence is abusive. The use of marijuana as a herbal medication is being widely discussed in literature. The most promising effect of delta-9-etrahydrocannabinol seems to be observed in the case of nausea, following cancer chemotherapy. Despite its positive action on the human organism, marijuana smoking has been shown to exert adverse effects on the cardiovascular system causing well-tolerated tachycardia and/or hypotension. We also observed that marijuana abuse was associated with an increased risk of paroxysmal atrial fibrillation. The report presents a case of young healthy white subject suffering from paroxysmal atrial fibrillation following marijuana intoxication. The abuse of this substance was the most possible and identifiable risk factor for observed paroxysmal atrial fibrillation.