Objectives Previous investigations on microalbuminuria in acute myocardial infarction have been performed in heterogeneous populations of hypetensive/nonhypertensive, diabetic/nondiabetic patients, submitted to either thrombolysis or mechanical revascularization or not revascularized. Therefore, the aim of our investigation was to assess, in 242 consecutive hypertensive patients with ST elevation myocardial infarction without previously known diabetes, all submitted to mechanical revascularization, whether microalbuminuria, in the early phase, has a prognostic role for in-hospital mortality or complications (acute pulmonary edema and arrhythmias). Methods The study population was divided into two groups according to microalbuminuria excretion: group A (microalbuminuria within the normal range); group B (microalbuminuria above the normal range). Results The incidence of microalbuminuria was 52.1% (126/242). No significant difference was detectable in the incidence of in-hospital mortality and complications between the two groups. Patients with microalbuminuria exhibit a larger infarct size as indicated by higher values of troponin I. Microalbuminuria was associated with higher values of glucose and a higher prevalence of insulin resistance. Conclusion In ST elevation myocardial infarction hypertensive patients without previously known diabetes, all submitted to mechanical revascularization, microalbuminuria is a common finding but it does not yield prognostic information about in-hospital mortality or complications. Interestingly it was associated with acute glucose dysmetabolism (as inferred by hyperglycemia and the prevalence of insulin resistance), thus suggesting that it can be considered part of the acute metabolic response to the acute coronary event. J Cardiovasc Med 11: 748-753 (C) 2010 Italian Federation of Cardiology.