ABSTRACT Background: Coroanary artery ectasia (CAE) defined a dilatation exceeding more than one-third of the coronary artery length with the diameter of the dilated segment measuring more than 1.5 times the diameter of a normal adjacent segment and 3-5% of coronary angiography presentation. CAE with underlying coronary artery disease is a dangerous due to increased exposure for adverse cardiac events.The aim of the present study to predictacute coronary syndrome (ACS) among patients with coronary ectasia and slow flow.Patients and Methods:We studied 56patients with coronary artery Ectasia and divide them into two groups(case and control group) according to presentation as chronic coronary syndrome (CCS)or ACS.Full history taking and through clinical examination and specific investigation were performed for all patients. Both groups are stabilized and followed up for 6months for developing ACS.Results:we found that there was no statistically significant difference between both groups as regard demographic data that make both groups were well cross-matched also we found no significant relation for occurrence of ACS among patients with coronary Ectasia during follow up.There is statistically non-significant difference between the studied groups regarding obesity, smoking, comorbid diabetes, hypertension, dyslipidemia or family history of CAD.According to ACS encountered in ACS patients, 32.1% had NSTEMI, 28.6% had unstable angina, 17.9% had anterior MI and 17.9% had inferior MI.There is statistically non-significant relation between development of ACS among the studied patients and treatment used for ectasia. Single antiplatelet indefinitely increase risk (62.5% of those with ACS were on single therapy versus 0% within those who did not develop ACS).NOACS, Warfarin and double antiplatelet decrease risk of ACS (COR were 0.2, 0.27, and 0.35 respectively). Conclusions: We can predict occurrence of ACS among patients with coronary ectasia,use noninvasive traditional and laboratory risk factors for this prediction and prescribe the best managment for prevention of ACS recurrence.