Glomerular hyperfiltration and albuminuria are two pathological conditions that could alter renal drug elimination, but they have been rarely studied in a critical care setting. The aims of this descriptive, prospective study performed on 89 critically ill patients are to determine rates of glomerular hyperfiltration (main objective) and albuminuria (secondary objective). On admission, 17.9% of patients presented with glomerular hyperfiltration, climbing to rates as high as 30% during the first week of admission. Seventy-five percent showed albuminuria on admission, with rates remaining high throughout the week of the study. Since glomerular hyperfiltration as well as albuminuria are frequent pathophysiological conditions in critical care patients, the implications that these phenomena may have regarding drug elimination need further evaluation.