Background: Some patients with psoriasis may require hospital admission to stabilize their condition, although the role of inpatient management is changing given recent advances in therapeutic options, emphasis on community-based care for chronic conditions and limited healthcare resources. There is a need for evidence-based national standards for inpatient management of psoriasis taking account of factors that predict length of stay. Objectives: To determine which factors predict length of stay for patients with psoriasis requiring inpatient hospital care with a view to setting evidence-based standards for inpatient psoriasis management. Methods: A multicentre service review was conducted on all psoriasis admissions over a 9-month period in four dermatology centres in the U.K. We collected data on admission, at discharge and, where possible, at 3 months following discharge. Psoriasis severity was assessed using four validated scoring systems, including Psoriasis Area and Severity Index (PASI) and Dermatology Life Quality Index. We also recorded length of stay and treatment details. Results: Length of stay varied widely between the four centres, but was similar in the two centres which received a high proportion of tertiary referrals for severe psoriasis (mean 19.7 days, range 1-78, analysis of variance P = 0.002). Disease severity, measured by PASI, on admission (mean 15.7, interquartile range 8.3-20.8) was significantly higher in the tertiary centres (P <0.0001). However, there was no significant difference in PASI between centres on discharge. The admission PASI was significantly associated with length of stay (r = 0.2, P = 0.02). There was no significant correlation between other measures of disease severity and length of stay. Conclusions: Disease severity on admission for patients with psoriasis is greater in tertiary referral centres for psoriasis and is directly associated with length of stay. Length of stay should be used in conjunction with clinical measures such as PASI improvement to set national standards for quality in secondary care. © 2007 The Authors.