Inflammation and oxidative stress take part in the development of the pathogenesis of acute coronary syndromes (ACS). The aim of this study was to analyze serum concentrations of high sensitivity C-reactive protein (PCR-as) and malondialdehyde (MDA) in cocaine consumer patients and ACS. We carried out a retrospective analysis of 43 patients with ACS and a positive urine test for cocaine, who were compared to a sample of 49 patients with this diagnosis and a negative test. We evaluated the clinical, laboratory, electrocardiographic and hemodynamic features. Both groups were similar in clinical, laboratory, electrocardiographic and hemodynamic features, except those patients with ACS and a positive cocaine test who were younger and had a predominantly transient ST-segment elevation. PCR-as values were lower in the ACS and cocaine positive group (4.82+/-0.67 versus 5.34+/-0.81mg/L, p <0.0035). In contrast, MDA concentrations were higher (0.66+/-0.50 versus 0.31+/-0.09nmol/ml, p <0.0001). Likewise, in the multivariate analysis, patients with ACS and cocaine positive test were related, on an independent form, to oxidative stress. Oxidative stress plays a major role on inflammation in the different mechanisms involving cocaine in the pathogenesis of ACS, independently of the age and cardiovascular risk factors.