Background: Amphotericin B is the agent of choice for most invasive fungal infections in critically ill patients. It is associated with at least a 50% incidence of nephrotoxicity despite prophylactic measures such as sodium loading. Newer formulations of amphotericin B are available but are costly and have unknown bioavailability in critically ill patients. Previous trials in neutropenic and critically ill patients have demonstrated that mixing amphotericin B with 20% lipid solution (Intralipid; Clintec Nutrition, Deerfield, III) may decrease nephrotoxicity. Methods: In this randomized, prospective clinical trial, patients with positive fungal blood cultures, tracheal/sputum cultures or peritoneal cavity cultures were randomized to receive either 0.5 mg/kg per day of amphotericin B dextrose or 1.0 mg/kg per day of amphotericin B lipid emulsion. Duration of therapy was determined by the primary care team. Weekly 24-hour creatinine clearance was measured until 2 weeks after amphotericin B therapy was completed. Results: The two groups were similar based on age, white blood cell count, serum creatinine, and creatinine clearance at the beginning of therapy, The group receiving amphotericin B lipid emulsion had significantly less decrease in creatinine clearance compared with controls, despite receiving significantly more amphotericin B. Conclusion: Amphotericin B lipid emulsion can be given at a higher total cumulative dose than amphotericin B dextrose with less nephrotoxicity.