BACKGROUND: The live measles vaccine has been associated with lower non-measles mortality and admissions in low-income countries. The live measles-mumps-rubella vaccine has also been associated with lower rate of admissions with any type of infection in Danish children; the association was strongest for admissions with lower respiratory infections. OBJECTIVE: To examine whether measles, mumps, and rubella (MMR) vaccination was associated with reduced rate of hospital contact related to respiratory syncytial virus (RSV) in a high-income country. METHODS: Nationwide cohort study of laboratory-confirmed RSV hospital contacts at age 14-23 months in all children born in Denmark 1997-2002 who had already received the vaccine against diphtheria, tetanus, pertussis (acellular), polio, and Haemophilus influenzae type b (DTaP-IPV-Hib) at the recommended ages of 3, 5, and 12 months. RESULTS: The study included 888 RSV hospital contacts in 128,588 person years of follow up (rate 6.8/1000 person years). Having MMR as the most recent vaccine was associated with a reduced rate of RSV hospital contacts compared with having DTaP-IPV-Hib as the most recent vaccine (Incidence rate ratio (IRR), 0.75; 95% confidence interval (CI), 0.63-0.89). After adjustment for potential confounders including exact age in days the IRR was 0.78 (95% CI, 0.66-0.93). The adjusted IRR was 0.74 (95% CI, 0.60-0.92) in males and 0.84 (95% CI, 0.66-1.06) in females (P Interaction, 0.42). There was no association in the first month after MMR vaccination (adjusted IRR, 0.97; 95% CI, 0.76-1.24) but the adjusted IRR was 0.70 (95% CI, 0.58-0.85) from one month after MMR vaccination. CONCLUSIONS: MMR vaccination was associated with reduced rate of hospital contacts related to laboratory-confirmed RSV infection. Further research on the association between MMR vaccination and other unrelated pathogens are warranted.