This paper reports an attempt to assess the factors associated with inappropriate acute hospital admission using the technique of logistic regression. Data were obtained from two separate studies of acute hospital utilization in south-west England, conducted between 1992 and 1994. The appropriateness of admission was assessed using explicit standardized criteria in the form of the intensity-severity-discharge review system with adult criteria (ISD-A). Up to 19 explanatory variables were available for the analyses. These variables were modelled for each centre separately, using logistic regression to produce final sets of factors independently related to the appropriateness of admission. For one centre, the final model contained age/ specialty and use of community services. For the other, the final model contained two measures of health status on admission-coping failure and admission with stroke. It is concluded that the complex interplay between the characteristics of patients, referrers, alternative forms of care and the acute hospital may result in quite different types of inappropriate admissions in different locations.