In this study a monitoring technique was employed to examine the role of the syllable in the perceptual segmentation of words. Pairs of words sharing the first three phonemes but having different syllabic structure (for instance, pa-lace and pal-mier) were used. The targets were the sequences composed of either the first two or three phonemes of the word (for instance, pa and pal). The results showed that reaction times to targets which correspond to the first syllable of the word were faster than those that did not, independently of the target size. In a second experiment, two target types, V and VC (for instance, a and al in the two target words above) were used with the same experimental list as in experiment one. Subjects detected the VC target type faster when it belonged to the first syllable than when it belonged to the first two syllables. No differences were observed for the V target type which was in the first syllable in both cases. On the basis of the reported results an interpretation in which the syllable is considered a processing unit in speech perception is advanced.