Review of MEDLINE and International Pharmaceutical Abstracts from 1966 to the present. Study design was not a factor in selecting literature for this review. All studies, case reports, and case series describing infusion of a loop diuretic are included. Cited literature was found in peer-reviewed clinical or basic science journals. There is a pharmacodynamic basis for the use of a controlled infusion of the loop diuretics in critically ill patients requiring extensive diuresis. Animal and human volunteer studies have demonstrated a clear improvement in efficiency of diuresis by controlled infusion. Clinical studies in critically ill patients have demonstrated an improved diuretic response with a controlled infusion. Adverse effects appear to be minimal, and the amount of drug required for effect is less than the required amount for bolus administration. Administration of loop diuretics by continuous intravenous infusion may improve diuresis in critically ill patients who require prompt, controllable diuresis, or who demonstrate “diuretic tolerance” to conventional administration regimens. Despite few, well-designed studies using this method of administration in clinical practice, pharmacodynamic concepts support continuous infusion over bolus administration, including decreased dosage requirements, improved diuretic response and few adverse effects. (Crit Care Med 1994; 22:1323–1329)