High resolution ultrasound can be used for the accurate measurement of intima-media thickness (IMT). The within-observer coefficient of variation of the IMT of two carotids measured seven times each on different days by two different observers was between 4% and 8%, and the mean absolute difference of the IMT of 68 carotids measured independently by two observers was 0.11 +/- 0.11 mm (mean value +/- SD). Seventy-five consecutive male patients who underwent coronary angiography for assessment of chest pain and 40 normal controls matched for age and sex, were examined with high resolution B-mode ultrasound. The IMT of the common carotid artery for the controls was 0.71 +/- 0.16 mm and for the patients 0.91 +/- 0.18 mm (P < 0.005). In patients with normal coronary angiogram the IMT was 0.73 +/- 0.1 mm, and this increased in each of the subgroups with coronary stenosis compared to patients who had a normal coronary angiogram. In the group with one-vessel disease it was 0.91 +/- 0.17 mm (P < 0.05, ANOVA), in the group with two-vessel disease it was 0.96 +/- 0.17 mm (P < 0.01), and in the group with three-vessel disease it was 0.99 +/- 0.21 mm (P < 0.01). There was a significant linear trend between IMT and the number of involved vessels (P < 0.0001, r = 0.44). An IMT > or = 0.85 mm was derived from the studied population of 75 patients as a criterion for the prediction of coronary artery disease (CAD).(ABSTRACT TRUNCATED AT 250 WORDS)