MALDI-TOF MS was used to study the end group distribution of a series of poly(p-phenylene terephthalamide) and Kevlar fibers. Poly(p-phenylene terephthalamide) fibers were synthesized using various percent mole ratios of diamine-to-diacid chloride (70:30, 51:49, 50:50, 49:51, and 30:70), and their resulting MALDI-TOF mass spectra were compared with the mass spectra of Kevlar fibers. Oligomers synthesized with excess diamine or excess diacid chloride were found to contain abundances of amine or carboxylate end groups, respectively, along with side products that were specific to their synthesis. Oligomers synthesized with near equimolar ratios of reactants produced dominant species with amine-carboxyl end groups along with small quantities of cyclic and imine branched species, which were also found in the oligomeric portion of commercially produced Kevlar. Experimental results from this study indicate that mass spectra derived from the oligomeric portion of high molecular weight polymers can yield useful information about their synthesis.