Reproducibility of MIC results between laboratories, a major performance criterion used for evaluation of any susceptibility test method, was determined at three test sites using the Sensititre YeastOne Antifungal Panel, which incorporates Alamar Blue as a colorimetric indicator. MICs of five antifungals were determined using a set of 10 isolates of Candida species. Each isolate was tested a total of nine times against each antifungal agent in each of the three laboratories. A total of 1350 MICs were evaluated. MICs were read visually after incubation at 35 degrees C for 24 and 48 h. Overall, 99 to 100% of MIC values were encompassed by a range defined by the modal MIC +/- 1 dilution for each antifungal agent tested at both 24 h and 48 h. Replicate testing of the quality control isolates recommended by the National Committee for Clinical Laboratory Standards demonstrated excellent agreement between results obtained with the Sensititre YeastOne panel and the MIC reference range for each antifungal agent. These studies demonstrated that the Sensititre YeastOne Antifungal Panel may be used to generate MIC values for at least five different antifungal agents with a high degree of intra- and interlaboratory reproducibility.