The relationship between blood pressure, ponderal index, sex, blood glucose, haemoglobin, serum uric acid, calcium cholesterol and creatinine, and albumin has been examined in 698 subjects aged between 44 and 49 years from the register of a group general practice. Sixty per cent of the variation in systolic pressure could be explained by statistically significant associations with diastolic pressure, sex, blood glucose, serum calcium, and cholesterol. The diastolic blood pressure (not corrected for systolic pressure) was significantly related only to ponderal index, haemoglobin in men, and cholesterol in women. Pulse pressure was also positively related to the risk factors blood glucose, serum cholesterol, and calcium. The possibility is discussed that one or more of these variables reduce aortic compliance and that the serum calcium contributes to this end. Diastolic, but not systolic pressure, had a prime association with relative weight, obesity being only basically associated with an increase in diastolic pressure.