Background/aims. The purpose of this study was to examine characteristics of disfluency clusters in adults who stutter (AWS) and to compare these characteristics to those previously reported for children who stutter (CWS). Method. The spontaneous speech of ten AWS was sampled and organized according to utterance length in syllables. The overall number and type of disfluency clusters occurring in each sample were determined. Results. Findings indicated that utterances containing disfluency clusters were significantly longer than fluent utterances, and the occurrence of disfluency clusters was correlated with overall percentage of disfluency. Conclusion. The results obtained in the present study for AWS tend to parallel those found for CWS and serve to validate their occurrence as a feature of the disorder of stuttering.