Twenty-two psoriatic patients were treated orally with the antichemotactic agent, colchicine, at a dosage of 0.02 mg per kg per day for a duration of 2-4 months. Complete clearing or marked improvement were noted in 8 of the 9 patients, in whom thin papules and thin plaques were the predominant type of lesion. Much less favorable results were obtained in patients with chronic, stable, thick plaque-type disease, although decreased scaliness, erythema and infiltration and marked diminution of the pruritus were observed in almost all of the cases. A considerable improvement of the joint pains was noted in each of the 8 patients who suffered from arthralgias. Five additional patients with extensive, chronic, stable plaque-type psoriasis were given oral colchicine immediately after complete clearing of their skin lesions with Goeckerman's method or with methotrexate. Four of them continued to take colchicine for 8-9 months and during that time they remained free of significant skin disease. These findings lend support to the hypothesis that the migration of the activated psoriatic neutrophils into the skin could be an important factor in the initiation and possibly also in the perpetuation of the psoriatic lesions. Closely controlled, long-term studies conducted in large numbers of patients are warranted in order to determine the exact therapeutic role of oral colchicine in the long-term management of psoriasis.