This study is part of the research project 'geMMA' (www.gemma-kiel.de), examining the spectrum of pathogens involved in sows' Postpartum Dysgalactia Syndrome (PPDS) and analysing risk factors concerning this complex puerperal disease. PPDS represents an important disease in sows after farrowing. Serious economic losses come along with the disease due to reduced performance of the sows and increased mortality of the piglets. Prevalence in herds can be as high as 60%. The aetiology of PPDS is multifactorial. Husbandry, management, feeding and hygiene are regarded as influencing factors. Bacterial pathogens are of great importance, but detailed information is lacking. Milk samples of 421 sows with PPDS and 449 non-infected sows of different age were taken on six piglet rearing and fattening units and analysed statistically. Sows were identified as PPDS-infected when the measured temperature was above 39.5°C.