To study the rates of catheter associated urinary tract infection (CAUTI), Ventilator-associated pneumonia (VAP), Central venous catheter blood stream infection (CVCBSI) and surgical site infection (SSI) in Thai hospitals. The rates of the infections will be used as quality indicators.Active surveillance in 38 hospitals in Thailand during 2003-2004. Risk stratification of NI rates and utilization of devices were calculated.The rates of CAUTI, VAP, CVCBSI and SSI were obtained. Pooled means, and rates of NI at 10, 25, 50, 75 and 90 percentiles were calculated for CAUTI, VAP, CVCBSI. The infection rates were also presented for each type of hospital. The above NI rates were comparable to those reported by the National Nosocomial Infection Surveillance System (NNIS) in the United States. Surgical site infection was studied in 21 procedures with risk index categories 0-2. The rates of SSI in the present study was lower than those in the U.S. study due to different methods of study.The risk stratified rates of CAUTI, VAP, CVCBSI and SSI were obtained. They were similar to a larger scale of study in the United States. The NI rates could be used for evaluating the efficacy of NI control in Thai hospitals.