Fifty-one patients with psoriasis were treated with 1% anthralin for 1 h (1-h treatment) and UV-light. Seven of 11 out-patients treated with anthralin and UV-B showed a good response. In 40 in-patients the 1-h regimen was administered in right-left side comparison to evaluate (1) whether UV-A or UV-B combined with anthralin was more effective than anthralin alone and (2) whether anthralin was photoactivated by UV-A or UV-B. As to the latter, one body side of the patients was exposed to UV radiation before and the other body side after application of anthralin. In in-patients the response to therapy was monitored by a defined score system. We did not find any significant differences in the paired comparisons. We therefore summarized the different treatment regimens and rated 42% with very good or good, 26% with fair, and 32% with poor. The results show that the 1-h treatment with 1% anthralin seems to be advantageous especially for the treatment of out-patients with circumscribed chronic psoriatic lesions. UV-light did not improve considerably the therapeutic effect of anthralin in the regimen of this study.