A prospective cross-sectional questionnaire study of 32 patients with psoriasis was carried out in order to validate the use of the Sickness Impact Profile (SIP) in psoriasis and compare its sensitivity with the Psoriasis Disability Index (PDI). Overall PDI scores, but not overall SIP scores, correlated well with PASI scores (P less than 0.05). There was good correlation between the PDI and overall SIP scores (P less than 0.01). Psychosocial factors are more severely impaired than physical activities in patients with psoriasis. It is now possible to directly compare the disability experienced by psoriatic patients with that experienced by patients suffering from other systemic diseases, using the SIP. The PDI is an appropriate method to give a rapid overall measure of psoriasis disability.