For captive primates, environmental enrichment may improve psychological well-being, as indicated by changes in the frequency of species-typical and abnormal behaviours. The effects of enrichment on physical well-being have also been examined, but little attention has been devoted to the relationship between enrichment and animal health. We therefore studied the health records of 98 rhesus macaques (Macaca mulatta) to measure the effects that enrichment and social housing manipulations had on the number of veterinary treatments and days of therapy required by the monkeys. Subjects were housed singly, in pairs and in groups. Half of the subjects in each housing condition were enriched and the others were controls. Control and enriched subjects did not differ in the number of treatments they required, but enriched subjects received longer therapies than did controls. Neither treatments nor days of therapy were frequent or randomly distributed across housing conditions; pair-housed subjects required the least treatment and therapy, whereas singly-housed subjects were treated slightly more frequently for diarrhoea-related problems, and group-housed subjects for trauma-related problems. Subject age, however, was a potential confounding factor. Because subjects were part of a specific pathogen-free breeding programme, they spent only certain ages in each housing condition. Results suggest that inanimate enrichment neither diminishes nor improves the health of young macaques, but that enriched monkeys may require longer periods of therapy than do controls. Pair housing may be an effective housing strategy from both veterinary and behavioural points of view, necessitating relatively few treatments, but providing some social enrichment opportunities.