AbstractBackground: The Coronary Slow Flow Phenomenon (CSFP) is sometimes seen amongst patients presenting with ACS, in particular unstable angina and rarely with Normal Epicardial Coronaries (NECA). The study attempts to identify predictors of CSFP in patients with classical angina and normal epicardial coronaries in Asian Indians. Materials and Methods: This was a prospective, open label, observational study of 3000 consecutive patients undergoing invasive coronary angiography that was carried out a tertiary level cardiac care center between August 2016 to December 2018. After identifying the prevalence of CSFP using the corrected TFC method in allcomers, equal numbers of controls were analyzed for detailed evaluation for traditional risk factors, history, clinical examination, and laboratory investigation. Results: CSFP was more prevalent in men than in women (P=0.007). Histories of smoking and hypertension were more prevalent in CSFP patients than in NECA patients statistically significant (50% vs 20%; p 0.02) and (66.7% vs 33.3%, P 0.009) with Odds Ratio (OR) of 4(95% CI 1.27 to 12.58; P 0.02) for smoking and 4(95% CI 1.37 to 11.7; P0.01) for hypertension. Presence of LV dysfunction (16.7% versus 10%, P 0.45) with OR 0.56(95% CI 0.12 to 2.57; P 0.45), high level of hemoglobin in CSFP group (14.17±1.45 vs 11.95±1.38 mg/dl; p <0.0001), high level of LDL-c (153.77±13.02 vs 92.37±11.45 mg/dl; p <0.0001) and low HDL-C (33.93±6.71 vs 55.60±5.78mg/dl; p <0.0001) were also independent predictors of CSFP. Amongst single vessel CSFP, LAD was most common vessel (40.4%). Conclusion: Prevalence of CSFP amongst Asian Indians is 1%. High LDL-c, Low HDL-c level, Smoking, elevated hemoglobin and Hypertension are independent predictors of CSFP.