Long call vocalizations were recorded in the field from four adjacent subspecies of the saddle-back tamarin, Saguinus fusckollis ssp. Quantitative measurements of several call parameters were analyzed and four variables were found to be significantly different across subspecies. Each of the four subspecies had a distinctive set of long call parameters. One animal's call was a mosaic of its own subspecies call and that of the subspecies found directly across the river. Recordings of captive hybrids of the same two subspecies showed components of only one of the parental calls, and of calls of another subspecies with which they were housed. Long call structures of subspecies of Saguinus fusckollis are useful for studies of vocal ontogeny and identification of subspecies.