AIM OF STUDY: To compare the utility and reliability of coronary angiography with multislice computed tomography (MSCT) and by cardiac catheterisation in assessing atherosclerotic lesions and stenosis. MATERIAL AND METHODS: Data were assessed from 44 subjects (25 men, 19 women) (mean age 63 years; range 34-80 years) referred to MSCT who also had undergone invasive coronary angiography within a time frame of one year. Coronary angiograms from both studies were assessed by segmental analysis and the atherosclerotic severity graded. The frequency of coronary calcification on MSCT was separately assessed in 150 subjects. RESULTS: By retrospective evaluation, 29 segments were found to have significant stenosis (> or = 50%) on the invasive coronary angiogram. Of these 17 had a diameter over 2.0 mm and 14 (83%) thereof were correctly diagnosed by MSCT. On the other hand, MSCT assessed four stenosis to be significant that were not judged so on the invasive angiogram. On MSCT, the frequency of coronary calcifications increased with age and in those 60 years and older it was 96% in males and 71% in females (p=0.025). CONCLUSION: Good agreement was found between MSCT and invasive coronary angiography in assessing significant stenosis in vessel segments over 2.0 mm. In older subjects coronary calcification on MSCT is frequent and diminishes its accuracy. MSCT seems most useful in relatively young subjects in whom the coronary arteries need to be evaluated to avoid unnecessary cardiac catheterisation.