Nosocomial infections are a major problem worldwide. The literature shows that nosocomial infections are problematic in developed countries and developing countries but a little is known about the prevalence of nosocomial infections in different countries includes Rwanda. This research aimed to explore the prevalence of nosocomial infections in the Butare University Teaching Hospital in Rwanda. The past is the foundation of the future, reason why looking behind gives overview of current event and help in planning the future accordingly. A retrospective, descriptive design guided the research process.