Hemophilia A and B are X-linked bleeding disorders characterized by the absence or reduced activity of coagulation caused by mutations in the factor VIII and factor IX genes, respectively. Diagnosis of hemophilia is based on understanding the clinical features and symptoms of hemophilia, screening tests to determine the potential cause of bleeding such as prothrombin time, activated partial thromboplastin time, platelet count and function, and specific investigations such as factor analysis and confirmation of the diagnosis with appropriate methods. In this review, it is aimed to give detailed information about the biochemical tests used in the diagnosis and follow-up of Hemophilia, their usage algorithms, mixture tests, factor and factor inhibitor tests.