Although acute peritoneal dialysis is a useful procedure, peritonitis is often a complication. When the patient is mainly at risk of peritonitis is controversial. The purpose of this study was to find the incidence time of peritonitis, the infecting microorganism, and risk factors.A retrospective study.118 cases of acute peritoneal dialysis in 93 patients were included in this study.Data were collected from medical records.Overall, the peritonitis rate was 36.45 per cent. The peritonitis rate rose following the duration of dialysis from 11 per cent on the first day to 21 per cent on the third day, although the difference was not statistically significant. Gram-negative bacilli were predominant, at 81.6 per cent. Acinetobacter baumanii and Enterobacter cloacae were the two most common organisms (23.7 and 21.1% respectively). There was a significantly higher male to female ratio in the peritonitis group than the no-peritonitis group (3.33:1 and 1.2:1 respectively, p=0.028).There was a high peritonitis rate in acute peritoneal dialysis. The most common microorganisms were gram-negative bacilli, Acinetobacter baumanii and Enterobacter cloacae. The risk factor was male sex. Duration of dialysis of more than 2 days tended to increase the risk of peritonitis.