The efficacy and safety of Amphotericin B Colloidal Dispersion (ABCD) have been investigated on 572 patients in five Phase I/II clinical trials. The patients were all selected to present a challenging test; having a fungal infection superimposed on severe illness. In 442 cases ABCD was used after amphotericin B, which had been withdrawn. One hundred and forty patients had pre-existing nephrotoxicity. Most patients received doses of 3-6 mg/kg/day of ABCD. Complete or partial recovery was reported in 149/260 (57.3%) patients evaluable for therapeutic response. Patients with Candida infection responded better than those with systemic aspergillosis showing 70.1% recovery vs. 48.8%. ABCD therapy made no difference to serum creatinine levels, even in patients with pre-existing renal failure, nor to liver function as measured by SGOT, alkaline phosphatase and total bilirubin levels in serum. Infusion-related adverse events were the most frequently reported side effects of ABCD. However these studies show clearly that ABCD can be administered safely to patients without the risks of renal toxicity, even when renal toxicity had already developed following therapy with conventional amphotericin B deoxycholate.