A rapid, reversed-phase liquid chromatographic method was developed for the assay of nystatin in the bulk drug and a variety of dosage forms. Analysis was performed on a Symmetry C18 reversed-phase column using a mobile phase of methanol-water-dimethylformamide (DMF; 55 + 30 + 15, v/v/v), with detection by UV at 305 nm. Quantitation is based on the sum of the peak areas of the 2 major isomers of nystatin. The linearity of the assay was determined for a concentration range of 0.05 to 0.2 mg/mL (correlation coefficient > 0.999). Accuracies and precision showed good reproducibility.