Saperconazole (R66905) is a broad-spectrum antifungal triazole and has potent activity against Aspergillus with an MIC90 of 0.19 mg/L. The antifungal activity of Saperconazole is complete at 1 μg/mL for all but one strain of A. niger. Eighty percent of all strains show complete absence of growth at 0.1 μg/mL (85% for A. fumigatus), and this result persists during 14 days of the test. All control pigeons infect with A. fumigatus die within 2 to 5 days. They have necrotic foci in the lungs, air sacs, liver, spleen, and kidneys. These organs are highly positive by histology and oncultures. Saperconazole administered at 2.5 mg/kg is not active, but when it is given at 5 or 10 mg/kg, 92 or 100%, respectively, survive and organ cultures are negative. No drug-related side effects are observed in the pigeons.