jats:pBackground: nowadays Wikipedia is one of the main on-line sources of general information. It contains several items about nosocomial infections and their prevention, together of items on virtually every scientific topic. This study aims to assess whether Wikipedia can be considered a reliable source for professional updating, concerning Healthcare-associated Infections (HAI). Methods: Wikipedia has been searched in order to gather items on HAI. 387 items were found with a search string. The field of research was reduced at those articles (27 items) containing exhaustive information in relation to prevention of HAI. The messages contained in those articles were than compared with the recommendations of a selected guideline (NICE 2003), completed by a literature search, with the aim of testing their reliability and exhaustivity. Results: 15 Wiki items were found and 51 messages selected. NICE guidelines contained 119 recommendations and 52 more recommendations has been found in a further literature search. 45.1% of Wikipedia’s messages were even found in the guidelines. On this percentage, 21.6% completely agreed with the messages of the guidelines, 15.7% partially agreed, 3.9% disagreed and 3.9% showed different level of evidence in different articles. Moreover, 54.9% of Wikipedia’s messages were not included in the guidelines and 84.2% of the recommendations contained in the guidelines were not present in Wikipedia. Conclusions: Wikipedia should not be considered as a reliable source for professional updating on HAI.</jats:p>