A loud call of the ruffed lemur (Varecia variegata) was analyzed for subspecific and gender differences according to four variables: pulse rate, median pulse duration, median high frequency, and median low frequency. These vocalizations of black-and-white and red ruffed lemurs and one hybrid ruffed lemur were recorded at the Duke University Primate Center (Durham, NC). Significant differences were found between subspecies but not between the sexes. Quantitative differences in this loud call of ruffed lemur subspecies indicate that these prosimians exhibit subspeciation trends similar to anthropoid primates for which comparable data exist. Preliminary data are presented that support the hypothesis that the vocalization functions as a terrestrial predator alarm call.