The in-vitro activity of D0870, a new triazole, was compared with amphotericin B (AMP B) and itraconazole (ITZ) against 40 Aspergillus isolates, which included 25 isolates of Aspergillus fumigatus, using a broth macro-dilution method at 37 degrees C. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) (killing of > or = 98%) were measured. For 40 isolates, geometric mean (GM) MIC values and ranges were D0870 10.55 and 2-32, ITZ 2.26 and 0.5-64, AMP B 2.42 and 1-64 mg/L. Differences in susceptibilities between species were apparent with Aspergillus flavus (n = 5) being the most susceptible to D0870 (GM 2.64, range 2-8 mg/L). MFC values were within one dilution of the MIC value for 90% of isolates (D0870 and ITZ) and 95% of isolates (AMP B). In reproducibility studies, seven, eight and four of eight isolates retested gave MIC results within one dilution for D0870, AMP B, and ITZ, respectively. Therefore, in-vitro mould testing with D0870 is feasible and reproducible with clear MIC and MFC end-points. D0870 is active against most Aspergillus spp., but at higher concentrations than either ITZ or AMP B.