The study was conducted over a two-year period and included 48 psoriatic patients with palmar and plantar lesions and 61 psoriatic patients without palmar and plantar lesions who served as controls. The objective was to establish the incidence of contact sensitization and its importance as the causative factor in palmar and plantar psoriasis. The most frequent contact allergens were: nickel sulphate, mercapto mix, balsam of Peru, potassium dichromate, mercury mix and fragrance mix. Patch tests were positive in 41.7% psoriatics with palmar-plantar psoriasis and in only 6.6% of psoriatics without palmar-plantar involvement. The study showed an increased incidence of contact allergy in patients with palmar-plantar psoriasis.