The child presented in this report received intravenous amphotericin B 0.5 mg/kg every 36 hours, for dialysis-associated Candida peritonitis. Just prior to her third dose of amphotericin B, the peritoneal fluid concentration of this drug was 0.1 mcg/ml, and the simultaneous serum level was 0.2 mcg/ml. An hour following the third amphotericin B dose, the peritoneal fluid and serum concentrations were 0.2 and 0.4 mcg/ml respectively. The minimal inhibitory concentration (MIC) of amphotericin B for the C. albicans isolated from this patient was 0.05 mcg/ml, and the minimal lethal concentration (MLC) was 0.1 mcg/ml. Treatment included concurrent 5-fluorocytosine, and catheter removal. This is the first time that measurements of concentrations of amphotericin B in the peritoneal fluid have been reported in a child with peritonitis.