Allocated risk of coronary heart disease, from a statistical basis, ha
s traditionally been divided between the effects of a series of well-r
ecognized biological markers (hypertension, elevated serum lipids and
cigarette smoking) and the potential contribution of psychological fac
tors, the most prominent of which, in recent times, has been the Type
A behaviour pattern. This article examines the possibility that Type A
behaviour, as reflected in Jenkins Activity Survey (JAS) Scale scores
, influences coronary risk through an effect on these established biol
ogical risk markers, either independently or through the mediating inf
luence of occupational dissatisfaction. The data suggest that some sca
les of the JAS do relate systematically to a composite biological inde
x of coronary risk, and that this relationship can be better understoo
d in terms of lifestyle than stress factors. The implications for the
behavioural prevention of coronary heart disease are discussed.