Introduction. Severe forms of psoriasis are indicated for systemic treatment with conventional and biological preparations . The former includes methotrexate, cyclosporin, acitretin and narrow-band ultraviolet B phototherapy but toxicity may limit the dose and duration of treatment. Currently used less toxic biological preparations include inhibitors of TNF-alpha (etanercept, adalimumab, infliximab) and the monoclonal antibody against IL 12/23 ustekinumab. We present our own more than five-year experience with the systemic treatment of severe forms of psoriasis using these preparations. Methods. A total of 66 patients treated with systemic therapy (except for phototherapy) were divided into groups based on treatment. Therapeutic doses were administered according to the recommendations of the manufacturer and dermatological societies. Standard PASI and BSA indexes were used to evaluate clinical condition at weeks 0, 12 and 24. Results. Differences in PASI score reduction and BSA index between patient groups treated with different preparations were statistically significant at monitored intervals. At week 12, PASI score was reduced by 75% or more in a significantly greater number of patients treated with infliximab + methotrexate than those treated with acitretin. At week 24, identical comparison showed a significantly greater number of patients treated with etanercept or adalimumab than those receiving methotrexate. For BSA index reduction by 50% or more, no statistically significant differences were found between patient groups during the follow-up period. Conclusion. Systemic therapy provides a significant benefit to patients with severe psoriasis. Biological preparations are more effective than conventional medications which are often limited by severe side-effects and generally less tolerated than biological treatments.