Toxic Shock Syndrome (TSS) secondary to mastitis is seldom described. We present a case of TSS due to postpartum mastitis caused by Methicillin-resistant Staphylococcus aureus (MRSA). Five weeks after giving birth to a healthy boy, a 23-year-old secundipara was readmitted to the hospital with a fever, systemic erythema, nausea, vomiting, diarrhea, diffuse myalgia, generalized itching, orthostatic syncopes, photophobia, oligurea and pain in the left breast. Laboratory data on admission revealed deteriorated renal and coagulation function. Adminstration of Vancomycin, Imipenem, dopamin and nafamostat mesilate was started immediately after admission, that was effective. The patient recuperated steadily over the next week with apparent desquamation of the skin on her face, breast and extremities especially palms and soles. MRSA isolated from her milk was coagulase type II producing toxic shock syndrome toxin-I (TSST-1) and enterotoxin C. Also immunoglobulin G against TSST-1 was not detected from her sera both on admission and on discharge, which suggested that the patient belongs to the high risk group of TSS recurrence.