A trial was carried out in 60 patients with relatively stable psoriasis to compare the effectiveness, tolerance and cosmetic properties of dithranol in a cream base (0.1% and 0.25%) or in the form of a soft paraffin ointment (0.25%). Patients were assigned at random to receive treatment with one or other of the three formulations, applied once daily, over a period of 4 weeks. Assessments were made initially and after 2 and 4 weeks of induration, redness, scaling and pruritus and during the trial of staining of clothes and linen, skin discolouration and burning. There was no significant difference in effect between dithranol cream 0.25% and dithranol ointment 0.25%, while both showed a better effect than dithranol cream 0.1% (p less than 0.05). The dithranol cream preparations were significantly better (p less than 0.05) than dithranol ointment 0.25% regarding all the cosmetic variables after 2 as well as after 4-weeks' treatment. The same applied to the patients' overall evaluation of the cosmetic acceptability. Three patients in the dithranol ointment group were considered as treatment failures. One of them refused to continue with the treatment due to burning and another due to burning and staining.