We investigated the efficacy of infection control measures against nosocomial pneumonia in geriatric wards. Cases with nosocomial pneumonia were retrospectively analyzed between January 1991 and March 1995. The study period was divided into four annual periods (periods 1, 2, 3 and 4). Period 1, January to December 1991, was applied as the cotrol. We investigated patients with nosocomial pneumonias in geriatric wards (190 beds) of AINO Memorial Hospital, affiliated with Nagasaki University. During the study period, nosocomial pneumonia significantly diminished. (period 1 vs periods 2, 3 and 4, p < 0.05, p < 0.05, p < 0.05, respectively). Major causative organisms of nosocomial pneumonia were MRSA and Pseudomonas aeruginosa. During the four periods, a significant reduction in cases with MRSA- and P. aeruginosa-induced nosocomial pneumonia was observed (MRSA: period 1 vs periods 2, 3 and 4, p < 0.05, p < 0.05, p < 0.01, respectively; P. aeruginosa: period 1 vs period 3, p < 0.01, period 2 vs periods 3 and 4, p < 0.01, p < 0.05, respectively). On the other hand, the improvement of decubitus ulcers was associated with a significant reduction in nosocomial pneumonia (period 1 vs. periods 2 and 3, p < 0.05 and p < 0.05, respectively). In conclusion, stringent infection control programs, including a cleaning in the upper airways by povidone iodine, are necessary in geriatric wards to reduce and prevent nosocomial pneumonia.