An extensive review of Gilbert's disease (unconjugated, non-hemolytic hyperbilirubinemia) is made with incidence not exactly determined, but it is a disease linked to hereditary factors. Two types of the disease, together with the controversy existing as to their pathogenesis are discussed. The clinical picture and all laboratory studies carried out to reach a diagnosis are reviewed. Also, the histopathology and treatment are briefly described. Two cases of this disease in the same family are presented.