In order to assess the prevalence of and risk factors for aminoglycoside-associated nephrotoxicity in intensive care units (ICUs), we evaluated 360 consecutive patients starting aminoglycoside therapy in an ICU. The patients had a baseline calculated glomerular filtration rate (cGFR) of >30 ml/min/1.73 m 2 . Among these patients, 209 (58%) developed aminoglycoside-associated nephrotoxicity (the acute kidney injury [AKI] group, which consisted of individuals with a decrease in cGFR of >20% from the baseline cGFR), while 151 did not (non-AKI group). Both groups had similar baseline cGFRs. The AKI group developed a lower cGFR nadir (45 ؎ 27 versus 79 ؎ 39 ml/min/1.73 m 2 for the non-AKI group; P < 0.001); was older (56 ؎ 18 years versus 52 ؎ 19 years for the non-AKI group; P ‫؍‬ 0.033); had a higher prevalence of diabetes (19.6% versus 9.3% for the non-AKI group; P ‫؍‬ 0.007); was more frequently treated with other nephrotoxic drugs (51% versus 38% for the non-AKI group; P ‫؍‬ 0.024); used iodinated contrast more frequently (18% versus 8% for the non-AKI group; P ‫؍‬ 0.0054); and showed a higher prevalence of hypotension (63% versus 44% for the non-AKI group; P ‫؍‬ 0.0003), shock (56% versus 31% for the non-AKI group; P < 0.0001), and jaundice (19% versus 8% for the non-AKI group; P ‫؍‬ 0.0036). The mortality rate was 44.5% for the AKI group and 29.1% for the non-AKI group (P ‫؍‬ 0.0031). A logistic regression model identified as significant (P < 0.05) the following independent factors that affected aminoglycoside-associated nephrotoxicity: a baseline cGFR of <60 ml/min/1.73 m 2 (odds ratio [OR], 0.42), diabetes (OR, 2.13), treatment with other nephrotoxins (OR, 1.61) or iodinated contrast (OR, 2.13), and hypotension (OR, 1.83). In conclusion, AKI was frequent among ICU patients receiving an aminoglycoside, and it was associated with a high rate of mortality. The presence of diabetes or hypotension and the use of other nephrotoxic drugs and iodinated contrast were independent risk factors for the development of aminoglycoside-associated nephrotoxicity.