Summary The National Taiwan University Hospital (NTUH) adopted international guidelines for surveillance and control of healthcare-associated infection (HCAI) in 1981. This report describes the secular trends in HCAI at the NTUH over the past 27 years according to site of infection, aetiological agents and control measures. Clinical and microbiological data were collected by infection prevention and control nurses using a standardised case-record form. Specific control programmes were implemented and/or intensified as needed. Poisson or negative binomial regression analysis was used to quantify time trends of the incidence of HCAI. The annual number of discharges increased from 25 074 to 91 234 with a parallel increase in the Charlson comorbidity index. Active HCAI surveillance and periodic feedback were associated with a marked decrease in surgical site infections from 1981 to 2007 (2.5 vs 0.5 episodes per 100 procedures, P < 0.0001). On the other hand, there was a 4.8-fold increase in bloodstream infections (BSIs) (0.39 vs 1.88 episodes per 100 discharges, P < 0.0001). The average annual increase of pathogen-specific HCAI incidence during 1981–2007 was 11.4% for meticillin-resistant Staphylococcus aureus (MRSA), 75.4% for extensively drug-resistant A. baumannii (XDRAB), and 7.5% for Candida albicans ( P < 0.0001, respectively). The infection prevention and control programme was upgraded in 2004 by implementing annual, intensive, project-based control programmes, and decreases in rates of HCAI, BSI, MRSA and XDRAB were observed. This long term study demonstrates the need to couple surveillance of HCAI with focused control programmes. Hospitals must invest in adequate manpower to accomplish these goals.