The study gives information on the healing frequency and time to relapse in a day care centre for UVB, UVB plus dithranol, and PUVA treatment. Psoriasis treatment must be repeated for many years and a psoriasis patient must come to terms with the fact that during a substantial part of the rest of his life, he must use some type of treatment. This makes it important that the treatment is pleasant and easy to carry out. The combination of sauna and UVB in a day care centre, or treatment with home solaria fulfill these demands. In view of this background I think that UVB treatment of psoriasis could be the treatment of choice for many psoriasis patients. About 80 percent of the patients heal with this treatment. For the rest of the patients, addition of dithranol or a switch to PUVA has proven to be effective. Median time to healing was about 8 weeks with UVB and UVB + dithranol whereas 12 weeks was necessary to achieve healing among PUVA patients with a poor response to UVB given earlier. The remission times were 9, 12 and 25 weeks for UVB, UVB + dithranol and PUVA-treatment respectively. In Gothenburg, we give 35.000 UVB treatments annually. An important question is the potential hazards connected with the therapy as we know that UV radiation is carcinogenic. According to our studies, the median amount of UVB radiation actually received per year from therapy is of the same magnitude as during outdoor work or certain outdoor activities. If UVB treatment is expanded we can expect an increased incidence of skin cancer of squamous cell type among this type of psoriasis patient even if the retrospective study we made showed no increased risk among people extensively treated with UVB in the past. The risk for psoriasis patients on a life long UVB treatment will probably be of the same order of magnitude as for outdoor workers. In comparison with other every day risks, the risk of dying from a skin cancer seems to be negligible. Regular check-ups by a dermatologist can reduce this risk close to zero.