Objective: To determine the relationship and prognosis value of microalbuminuria in acute coronary syndrome. Materials and Methods: Cross ambispective analytical study in 100 patients with ischemic symptoms of minutes of evolution; in patients with acute myocardial infarction, the criteria used were: Electrocardiographic changes of ST segment elevation not less than 0.1 mV in two bipolar leads or 0.2 mV in at least two contiguous precordial leads, or new blocking left branch of His bundle; in patients with unstable angina criteria were: ischemic electrocardiographic changes or injury, CKMB isoenzyme level less than 10% to total CK. The data were processed using the Epi-Info software version 3.5.3. and absolute frequencies, averages and Pearson correlation coefficient were determined. Results: The male, 64% in patients with AMI and 72% in those with unstable angina, showed the highest frequency; the average age for AMI was 62.5 ± 10.1 years olds; the average age for unstable angina was 60.4 ± 11.0 years olds; the microalbuminuria average in the AMI group was 207.4 ± 64.7 mg and 44.9 ± 40.0 mg in the group with angina. Patients with microalbuminuria> 200 mg were 14.4 times higher risk of complications associated with statistically significant prognostic value. Conclusions: The magnitude of microalbuminuria is directly related to the severity of acute coronary syndrome; higher concentrations are observed in acute myocardial infarction; microalbuminuria> 200 mg is is prognosis of complications