Summary. Psoriasis is a chronic skin disease characterized by epidermal hyperproliferation that is probably mediated by an immunologic reaction to particular epidermal, dermal or circulating immunogenic peptide. The inheritance of psoriasis within some families suggests the importance of genetic factors in the pathogenesis of the disease. Population based studies revealed that psoriasis is associated with HLA genes class I and II located on the chromosome 6. The highest risk of develop- ing psoriasis carries the HLA-Cw*0602 gene. The analysis of HLA polymorphism in Croatian patients also showed the importance of Cw*0602 allele in psoriasis susceptibility. Until now, eight different gene loci for psoriasis are mentioned in the OMIM (Online Mendelian Inheritance in Men) data base. Even though, the psoriasis association with HLA genes is doubtless, only some carriers of susceptible genes develop the disease. Therefore, some other genes except HLA genes as well as some environmental factors have a role in the pathogenesis of psoriasis.