OBJECTIVES: To compare the quality of uro-oncological Web sites, to assess for language or disease differences across Western languages, and to perform a longitudinal comparison between 2004 and 2009. Uro-oncological Internet information quality is considered variable but no comprehensive analysis exists. METHODS: Health on the Net (HON) principles may be applied to Web sites using an automated toolbar function. Using the Google search engine (http://www.Google.com), in 2004 and 2009, 2400 Web sites were assessed using the keywords prostate, bladder, kidney, and testicular cancer in English, French, German, and Spanish. The first 150 Web sites in each language had HON principles measured-a comparison between 2004 and 2009 was done. A further analysis of site sponsorship was undertaken. RESULTS: Regardless of language or cancer type, most sites are not HON accredited. English has consistently more than English, French, Spanish, or German. For the respective languages in 2009, prostate has the most (29, 14%, 16%, 12%), followed by bladder (29%, 22%, 14%, 13%), kidney (25%, 15%, 10%, 13%), and testis (26%, 19%, 7.11%). Significant differences were found comparing language and organ groups. The quality improved from 2004 to 2009. Nonprofit organizations (51%), government and/or educational (39%), commercial (20%), with urologists last (14%) were accredited. CONCLUSIONS: A lack of validation of most uro-oncological sites should be appreciated by urologists. Additionally, there is a discrepancy in quality and number of Web sites across uro-oncological diseases and major Western European languages, but with some improvement seen recently. We need to encourage informative, ethical, and reliable complimentary health Web sites on the Internet and direct patients to them.