Rare bleeding disorders (RBDs) comprise the inherited deficiencies of coagulation factors such as fibrinogen, factor (F)II, FV, FV fl FVIII, FVII, FX, FXI, and FXIII, and are usually transmitted as autosomal recessive disorders. Given the low prevalence of these coagulopathies, information about their genetic, clinical and laboratory characteristics is limited. The clinical symptoms of RCDs are extremely diverse in terms of bleeding type, site, severity, age at onset, and duration. The weak association between residual coagulant activity and clinical bleeding severity, or at times inexistent, correlation between the factor's residual levels and clinical manifestations in some RBDs makes it difficult to use a single criterion to classify such conditions. Standardization and customization of coagulation assays, full genome sequencing, and global clotting assays will significantly improve diagnosis of patients with RBDs.