Evaluations of efficacy of the new biologic therapies for psoriasis have used both physician-assessed endpoints and patient-reported outcome measures. The Psoriasis Area and Severity Index (PASI) is commonly used in clinical trials but is too labor intensive for clinical practice, which uses more subjective measures (physician global assessment [PGA] of change and Overall Lesion Severity [OLS] scale). Because psoriasis affects quality of life (QOL), patient-reported assessments of their satisfaction with treatment also are important. The purpose of this study was to evaluate some of the measurement tools used in clinical trials to make them more applicable to the practicing dermatologist. We used results of a placebo-controlled clinical study of efalizumab for the treatment of patients with moderate to severe plaque psoriasis. After treatment, ratings of improvement in psoriasis as measured by the PASI and PGA were closely aligned. It was noted the latter tool could provide a more practical and user-friendly evaluation in clinical practice. After 12 weekly subcutaneous injections of efalizumab, patients who achieved > or = 50% but < 75% improvement in PASI had treatment responses rated as primarily good or excellent using the PGA; additionally, the patients treated with efalizumab had statistically significant improvements (P<.001) in all patient-reported QOL assessments compared with placebo-treated patients, as did patients who achieved a > or = 75% improvement in PASI (PASI 75).