This study determined prevalence and risk factors for retrovirus infection in a large population of cats in Germany over a 10-year period. Client-owned cats (17,462) were tested for the presence of feline immunodeficiency virus (FIV) antibodies or feline leukaemia virus (FeLV) antigen. A subset of 100 cats was evaluated to determine their survival times. Of the 17,289 cats, 563 tested positive for anitibodies against FIV. The prevalence was 3.2% and did not change significantly between 1993 and 2002. FeLV antigen was found in 638 cats. The prevalence of FeLV decreased significantly during this time from 6% to 1%. Forty-two cats were positive for both viruses. Living in a multi-cat household did not influence the risk of retroviral infection. Risk factors for FIV infection were male gender, older age, mixed breed, access to outdoor, aggressive behavior, and FeLV co-infection. Risk factors for FeLV infection included contact with other cats, aggressive behavior, and FIV co-infection. Vaccination and testing programs appear to be effective in decreasing FeLV infection. The median survival time of FIV-infected cats was not significantly different from non-infected cats. FeLV-infected cats had significantly shorter median survival times than non-infected cats. [VT]