Puerperal infection is one of the most common obstetric complications which leads to certain serious sequelas for those parturients. The study of 92 postpartum women at Siriraj Hospital from April 1, 1980 to March 1, 1983 was conducted to investigate the risk factors of puerperal infection. All 92 cases were diagnosed for puerperal infection according to the criteria of the Joint Committee on Maternal Welfare. Irregular antenatal care or no antenatal care, sexual intercourse during the last week before delivery and pelvic examination during pregnancy were found to be important predisposing factors in the antepartum period. Pelvic examination during labor accounted for 78 per cent of the patients and played an important role, while operative obstetrics (30%) and concomitant diseases during pregnancy (27%) were the next significant factors.