This study tested a model derived from personality theory in which perceived stress, perceived social support, health-risk and health-promotion behaviours mediate the relationship between perfectionism and perceived physical health. A sample of 538 undergraduate students completed a web-based survey assessing multi-dimensional perfectionism, perceived stress, perceived social support, health behaviours, physical health and a scale tapping elements of the five-factor model of personality. Analyses that account for the effects of traits from the five-factor model (e.g., neuroticism, conscientiousness and extraversion) indicated that socially prescribed perfectionism was associated with poorer physical health and this association was fully mediated by higher levels of perceived stress and lower levels of perceived social support. Self-oriented perfectionism was related complexly to health such that it was related to poorer health via higher levels of perceived stress, but was also related to better health via higher levels of perceived social support. Our findings illustrate the need for considering key mediators of the link between perfectionism and poor health outcomes.