Recent studies have suggested that both adults and children are sensitive to information about phonological pattern frequency; however, the influence of phonological pattern frequency on speech production has not been studied extensively. The current study examined the effect of phonological pattern frequency on the fluency and flexibility of speech production. Normal- and fast- rate nonsense-word repetitions of three groups of participants (preschool children, school-aged children, and adults) were analyzed. Subjective ratings of the wordlikeness of nonsense words, percentage phonemes correctly repeated, mean duration, and durational variability were measured. In the first experiment, ratings of the wordlikeness of nonsense words were found to correlate with the pattern frequency of sequences embedded in them. In the second analysis, it was found that children, but not adults, repeated infrequent sequences of phonemes less accurately than frequent sequences. In the third experiment, infrequent sequences were produced with longer durations than frequent ones, with children demonstrating a larger difference between frequent and infrequent sequences than adults. Phonological pattern frequency also influenced variability in duration: infrequent sequences of sounds were more variable than frequent ones. Thus, there appears to be an influence of phonological pattern frequency on speech, and, for some measures, a larger effect size is noted for children.