Notes that complaints of poor memory and concentration are common in veterans of the 1991 Persian Gulf War as are other symptoms. Despite a large research effort, such symptoms remain largely unexplained. A comprehensive battery of neuropsychological tests and rating scales was administered to 341 UK servicemen (aged 22-62 yrs) who were returnees from the Gulf War and peace keeping duties in Bosnia, plus non-deployed military controls. All were drawn from a large randomized survey. Most were selected on the basis of impaired physical functioning defined operationally. Group comparisons reveal an association between physical functioning and symptoms of depression, post-traumatic stress reactions, increased anger and subjective cognitive failures. Poorer performance on some general cognitive measures, sequencing and attention was also seen in association with being 'ill', but virtually all differences disappeared after adjusting for depressed mood or multiple comparisons. Deployment was also associated with symptoms of post-traumatic stress and subjective cognitive failures, independently of health status, as well as minor general cognitive and constructional impairment.