Two hundred and ninety-nine paraffin-embedded human coronary artery sections from 68 autopsies, both male and female and with various causes of death, were examined for distribution of C-reactive protein (CRP) using the indirect immunofluorescence technique and high-resolution confocal microscopy. The results demonstrate, for the first time, the existence of CRP in human coronary arteries, with evidence of CRP deposits being associated with lipids within in the artery walls. Grades of CRP immunoreactivity positively correlate with relative intimal thickness and negatively correlate with relative lumen size. It is suggested, therefore, that CRP may be related to the development of atherosclerosis and that the development of coronary atherosclerosis is associated with a relapsing inflammatory/necrotic process occurring within the coronary intima.