Ultrabiomicroscopy is a novel high-frequency (55 MHz) ultrasound technique that could be used to non-invasively measure the vessel wall and separate the intima-media complex into measurements of intima and media thickness. Since no previous study has measured intima and media thickness separately in vivo in patients with coronary heart disease (CHD), the aim of the current study was to measure intima and intima-media thickness of the radial and the anterior tibial arteries among patients with CHD and healthy subjects (HS). Thirty-two patients with CHD and 46 HS underwent investigations with ultrabiomicroscopy measurements of the radial and anterior tibial arteries. Patients with CHD showed a 19% increase in intima thickness of the radial artery compared with HS (0.088 +/- 0.024 mm versus 0.074 +/- 0.015 mm; p < 0.015), whereas no difference was seen in media thickness. There were no differences in intima or media thickness within the anterior tibial arteries. In conclusion, CHD is associated with thickening of the intima of the radial artery whereas media thickness was unchanged compared with HS. Assessment of intima thickness by high-frequency ultrasound may provide a tool for non-invasive early detection of atherosclerosis.