The passage of antifungal agents into pulmonary parenchyma was studied in normal sheep prepared by cannulation of the right external jugular vein and the efferent duct of the right caudal mediastinal lymph node. Five sheep were given single, sequential, intravenous injections of flucytosine, ketoconazole, BAY n 7133, amphotericin B methyl ester, and amphotericin B. Venous blood plasma and pulmonary lymph were collected before infusion and from 5 min to 24 h postinfusion; the concentrations of the drugs were assayed by a well-agar diffusion method.