 In this study, the investigators will intend to compare the efficacy and safety of various doses of acitretin in a randomized double blind manner in patients with severe plaque-type psoriasis, by i studying the change PASI score from baseline as a measure of efficacy ii determining the frequency of side effects at various doses. Sixty patients will be recruited from Psoriasis Clinic of Department of Dermatology, Venerology and Leprology, PGIMER. Patients will be randomly assigned to one of the three groups: Group A, consisting of 20 patients, will be administered acitretin 25 mg day ,Group B, consisting of 20 patients, will be administered acitretin 35 mgday and GROUP C consisting of 20 patients, will be administered acitretin 50 mgday This therapy will be continued until PSORIASIS AREA AND SEVERITY INDEX PASI scores are reduced to 25 of the original scores or 12 weeks, whichever comes earlier. It is expected that acitretin at higher doses will be more efficacious . As the exact etiopathogenesis of psoriasis is not fully known, it is difficult to provide a definite cure to all patients, though the disease activity can be controlled to a great extent with various treatment modalities. However the dosage of acitretin be adjusted according to response of the patients and tolerability of side effects. 