Outpatient UVB phototherapy and inpatient tar therapy are commonly used treatments for psoriasis. In practice, the treatments often represent therapeutic alternatives, but while the use of UVB radiation has been the subject of many randomized controlled trials, the use of tar is purely empirical. We therefore conducted an audit to compare the efficacy of these two treatments for psoriasis. The case notes of 59 patients were reviewed and compared. Tar therapy had a significantly shorter overall treatment time than UVB therapy (3.4 vs 7.8 weeks, P < 0.0001), even though the patients treated with tar had a significantly higher disease severity score on admission (2.7 vs 1.9, P < 0.0001). Tar treatments were given significantly more frequently (6.4 per week) than UVB treatments (3.0 per week). The number of UVB treatments given during a completed course was not significantly different from the number of tar treatments. No difference in the outcome of the treatments was observed. The results suggest that both tar and UVB radiation will continue to be of clinical relevance to psoriasis therapy. Tar therapy seems to be faster, but this may be due to the higher number of weekly treatments. For hospitalized patients tar therapy seems to be superior to phototherapy, at least when UVB is not administered on every weekday. For outpatients it seems most reasonable to offer UVB treatment, because a complete treatment course involves fewer visits than tar therapy. In addition, phototherapy is cosmetically well accepted by nearly all patients and in that respect is superior to tar therapy.