Background. - Contrast-induced nephropathy (CIN) severely impacts patient morbidity and mortality, especially in patients with ST-segment elevation myocardial infarction treated by primary coronary angioplasty, whose renal function is often unknown at the time of contrast exposure. Aim. - We sought the incidence and factors predictive of CIN in patients treated by primary coronary angioplasty in our hospital; we also questioned the relevance of Mehran's risk score in this population. Methods. - We considered all patients admitted for primary coronary angioplasty between January 2010 and December 2011, and included 322 patients with complete data on renal function. CIN was defined as a relative (>= 25%) or absolute (>= 44 mu mol/L) increase in serum creatinine following contrast medium administration. We compared patients with or without CIN, to identify predictive factors, and investigated the effectiveness of Mehran's score using a receiver operating characteristic (ROC) curve, Youden's index and a likelihood ratio test. Results. - The incidence of CIN was 9.1%. A multivariable analysis identified two independent risk factors for CIN: impaired glomerular filtration rate and cardiogenic shock at admission (P < 0.05). An elevated Mehran's score was associated with increased incidence of ON, but statistical analysis revealed this score to have poor sensitivity, especially in high-risk patients. Youden's index was very low and the area under the ROC curve was 0.59 in our population. Conclusion. - Renal failure and cardiogenic shock at admission were independent predictors of CIN in our acute myocardial infarction population. Mehran's score added little to the discrimination of patients undergoing primary coronary angioplasty, particularly high-risk individuals.