Abstract: Nicolau syndrome (NS) is a very rare complication of intramuscular injections that leads to some degree of necrosis in skin, subcutaneous fat and muscles. The type of injected Drugs and wrong injection methods are the main factors for this iatrogenic syndrome. Here we report a 29 months boy, one of the Iranian children affected NS following the wrong intramuscular injection of Benzathine Penicillin. But he came back home without any major complication because of a good hospital care. Reports of mortality and severe morbidity of common injection drugs such as penicillin derivates will help to prevent such iatrogenic syndromes. Keywords: Nicolau syndrome, Benzathine Penicillin, Embolia Cutis Medicamentosa, Livedoid Dermatitis.