The puerperal mastitis is a staphylococcal infection of the lactating mamma cumulating during the third and fourth week after delivery. It is seen three times as often after hospital than after house delivery, and it is also more frequent with primiparae than with multiparae. The infection is caused by bacterial hospitalism. Most commonly mamilla and milkducts are infected via the child's nasopharynx. Mastitis rarely occurs in non-nursing women. Early diagnosis before the appearance of all classical inflammatory symptoms is important, to start the treatment with antibiotics before abscess formation takes place. We mentioned Fucidine, Oleandomycin and Oxacillin as staphylococcal-effective, penicillinase-resistent antibiotics. Additionally low-dose X-ray radiation may be given. In case of abscess formation local antibiotic-instillation combined with oral antibiotic treatment should be tried before incision. It is best to incise an abscess only after is complete breakdown. Complications to be looked for are maternal sepsis and staphylococcal infection of the newborn.