The thrombolysis in myocardial infarction (TIMI) frame count is a simple clinical tool for assessing quantitative indexes of coronary blood flow. In this study we aimed to evaluate the effects of long-term cigarette smoking on the TIMI frame count in patients with angiographically proven normal coronary arteries. Between May 2001 and January 2002, 41 habitual smokers and 41 sex-matched nonsmokers with angiographically proven normal coronary arteries were included in the study. The TIMI frame count was determined for each major coronary artery in each patient. The TIMI frame count of the smoking group was significantly higher than that of nonsmokers for all three coronary arteries: left anterior descending ( corrected), 39 +/- 13 vs 22 +/- 8; right coronary artery, 35 +/- 13 vs 24 +/- 11; and left circumflex artery, 37 +/- 13 vs 25 +/- 8 ( P < 0.001 for all). The smokers tended to be younger than nonsmokers ( 46 +/- 7 vs 49 +/- 9 years; P = 0.07). We have found that smokers with angiographically normal coronary arteries have a higher TIMI frame count than nonsmokers with angiographically normal coronary arteries. An increased TIMI frame count can be regarded as an index of the harmful effects of smoking on coronary circulation regardless of the underlying mechanism.