Background Coronary slow flow phenomenon (CSFP) is an important, angiographic clinical entity, but its etiology remains unclear. The purpose of this study was to explore the potential role of local coronary anatomic properties in the genesis of CSFP. Methods One hundred and thirty-one consecutive patients with CSFP and 131 patients with angiographically normal coronary flow were prospectively enrolled after documenting coronary flow by corrected thrombolysis in myocardial infarction frame count (CTFC). Local anatomic parameters including the tortuosity index (TI), the ostial-to-middle diameter ratio, the ostial-to-middle cross-sectional area ratio, and the number of distal branches (NDB) of arteries at end-systole were compared between patients with CSFP and controls. Results For each major coronary artery, CSFP patients had higher TI and NBD compared with controls (all P < 0.05). The diameter ratio and cross-sectional area ratio of the three major coronary arteries were higher in the CSFP group (P = 0.004 and 0.020, respectively). The TI (r = 0.476, P < 0.001) and NDB (r = 0.186, P = 0.004) were significantly correlated with CTFC. However, the higher TI (beta = 0.424, P < 0.001) was the only independent correlate to CTFC. Multivariate logistic analysis revealed that TI (adjusted odds ratio 1.17, 95% confidence interval 1.11-1.23, P < 0.001) and NDB (adjusted odds ratio 2.20, 95% confidence interval 1.50-3.21, P < 0.001) were independent predictors of CSFP. Conclusion The presence of CSFP was associated with higher tortuosity and more distal branches in coronary arteries, indicating that the anatomic properties of coronary arteries could also play a role in the pathogenesis of CSFP. Coron Artery Dis 23:174-180 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.