Psoriasis is an autoimmune, multigenetic skin disease whose inheritance mechanism is not fully established. In the world it appears in around 1 to 3% of the population, and in Croatia the prevalence is 1.6% of the population. It usually starts in childhood when the first episode is triggered by streptococcal pharyngitis. Psoriasis is a lifetime disease characterized by chronic and recurrent exacerbations followed by remission periods. This disease is both physically and emotionally exhausting. Studies have shown that millions of people in the world have the potential to develop psoriasis, but only with the appropriate combination of external and internal factors the disease can be clinically present. The most common disease triggers are stress , infections and various drugs. Four clinical forms of psoriasis are described: chronic plaque psoriasis, eruptive psoriasis, pustular psoriasis and erythrodermic psoriasis with chronic plaque psoriasis being the most common form of psoriasis. It is characterized by the appearance of sharpbound erythematosus plaques covered with silver scales. The predilection sites are: scalp, elbows, knees and sacral area. The most common comorbidity in psoriasis is psoriatic arthritis that affects 30-40% of patients, although accurate epidemiological data are not known. Psoriasis immunopathogenesis studies have allowed the development of the new specific and effective drugs, such as biologic therapy, which is a significant advance in psoriasis treatment due to the high efficacy and good safety profile.