factor (Rhodes et al., 1982). The standard procedure for assaying phenoloxidase activity described by Polacheck et al. (1982) requires extensive sample preparation. Appropriately grown cells must be broken gently by vortexing with glass beads to minimize loss of activity and the membranes collected by ultracentrifugation. The resultant membrane-rich samples must be assayed for protein content by the Bramhall method (Bramhall et al., 1969), which is itself tedious, and then be tested for phenoloxidase activity. Manual cell breakage among isolates of C. neoJbrmans varies with degree of encapsulation. The resulting differences in total percentage of cells broken, as well as the amount of vortexing time required to achieve that degree of breakage, introduce two potentially serious sources of sample variation into the protocol. Because of the complexity of the procedure and the heterogeneous nature of the sample that results, reproducibility in the assay is difficult to obtain. For these reasons, a simplified assay for cryptococcal phenoloxidase was sought. Choudary (1984) described a rapid assay for enzymatic analysis of yeast cytosol enzymes in situ. Candida utilis (Henneberg) Lodder and Kreger-van Rij cells were permeabilized prior to assay by treating with EDTA and dithiothreitol (DTT) followed by toluene-ethanol. Because the active site of the cryptococcal phenoloxidase is directed inward into the cytosol, an effort was made to adapt the method of Choudary (1984) for C. neoformans. Cells of C. neoformans NIH B-3501 were grown and starved as described by Polacheck et al. (1982) for phenoloxidase assay. The sample was then divided, and one part was processed according to the original protocol. The other portion of cells was further divided so that the effects of the different components of the permeabilization protocol could be assessed. The cells for the whole cell assays were suspended at 100 mg of wet weight (approximately 2 x 108 cells) per ml. The final concentration of broken cells would