Background: Shoulder discomfort/pain can have many causes, Glenohumeral osteoarthritis (GHOA) being of them. GHOA is characterized by degeneration of the articular cartilage and the subcondral bone, together with narrowing of the joint space. The diagnostic criteria for GHOA have poorly been investigated. The aim of this study is to evaluate the guidelines on how to diagnose GHOA, and whether these are evidence based or based on expert opinions. Both clinical and radiological diagnostic criteria are reviewed. Methods: Initially, information was collected from different medical institutions providing medical guidelines. The purpose of this was to find out whether relevant guidelines about GHOA existed or not. Subsequently, a systematic literature review was performed. The literature search was conducted together with a librarian on the 1st of February 2018. PubMed was the used search engine. Only English literature and articles published the last 15 years were considered. The initial selection of articles was based on the review of titles and the abstracts. The final selection process included full text review of the chosen articles. Results: The initial process showed that guidelines regarding the diagnostics of GHOA are lacking both internationally and in Norway. The literature available is based only on expert opinions. After performing the literature search, 21 studies were considered as relevant. Two of these reviewed clinical diagnostic criteria. Thirteen of the articles evaluated radiological classification systems. Six articles reviewed the critical shoulder angle (CSA). Conclusion: The existing literature on how to diagnose GHOA is based on expert opinions. More quality studies are desirable, both for clinical and radiological diagnostics of GHOA. CSA might have a diagnostic significance in the future.