A simple practical questionnaire technique for routine clinical use, the Dermatology Life Quality Index (DLQI) is described. One hundred and twenty patients with different skin diseases were asked about the impact of their disease and its treatment on their lives; a questionnaire, the DLQI, was developed based on their answers. The DLQI was then completed by 200 consecutive new-patients attending a dermatology clinic. This study confirmed that a topic eczema, psoriasis and generalized pruritus have a greater impact on quality of life than acne, basal cell carcinomas and viral warts. The DLQI was also completed by 100 healthy volunteers; their mean score was very low (1.6%, s.d. 3.5) compared with the mean score for the dermatology patients (24.2%, s.d. 20.9). The reliability of the DLQI was examined in 53 patients using a 1 week test-retest method and reliability was found to be high (γs=0.99).