Atopic dermatitis is a skin condition often complicated by colonization with Staphylococcus aureus, which increases the risk of infective endocarditis, skin cellulitis and osteomyelitis. Positive cultures for Staphylococcus aureus are obtained from 70% to 80% of wounds in patients with mediastinitis. Thus sternotomy carries increased risk of mediastinitis in patients with atopic dermatitis. We retrospectively reviewed 25 patients with atopic dermatitis who underwent cardiac surgery via a median sternotomy or thoracotomy from January 1997 to September 2010 at our institution. Postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus was found in 3 patients who had a median sternotomy. They were ultimately discharged in good condition. No mediastinitis occurred in patients undergoing thoracotomy. Mediastinitis may occur due to direct exposure of the bone marrow to methicillin-resistant Staphylococcus aureus in patients with atopic dermatitis whose skin is colonized with such bacteria. Thoracotomy may be a better surgical approach in patients with atopic dermatitis who require thoracic surgery.