Background The Health ofthe Nation Outcome Scales (HoNOS) were developed to assess the outcome of severe mental disorders in relation to the Health ofthe Nation Strategy for England.

Aims To validate the HoNOS.

Method One hundred and fifteen patients were assessed by key workers using HoNOS, and by research workers using SCAN, SBS, and SRPS, and completing HoNOS in the light ofthis additional material.

These assessments were repeated after 6 weeks.

Results The performance of HoNOS in the hands of keyworkers was generally poor, in relation both to the research workers'rating of Ho NOS and to the criterion instruments.

Performance was particularly poor when the change in scores was used as a measure ofoutcome.

Conclusions There are serious problems in using Ho NOS as a routine measure ofclinical status in busy psychiatric services.

Its performance is probably related to the training and experience of keyworkers.

Sequential ratings are not a good method for assessing outcome.

Managers and planners should be cautious in adopting HoNOS, but it is worthy ofconsideration in developing a suite of locally agreed outcome measures.

Declaration of interest This study was entirely funded by the Department of Health.