In light of recent canine distemper virus (CDV) epidemics, we set out to determine the historical significance of CDV infection in captive lions and tigers in Switzerland. The retrospective case material consisted of 42 lion and tiger necropsy cases from 1972 to 1992. Necropsy reports for all lions and tigers were reviewed. All existing paraffin tissues were immunohistochemically examined with a polyclonal antibody raised against CDV. The results for 19 of the 42 lions and tigers were classified as positive by immunohistochemistry; 23 results were negative or questionable. The results for four animals (three positive and one negative ) were further tested by in situ hybridization, and the results concurred with the immunohistochemistry findings. CDV infection of large cats is older and more widespread than previously thought. All large cats in captivity should be immunized even if canine distemper is not believed to be a problem for large cats in the area.