The mucopolysaccharidoses are a group of lysosomal disorders characterized by abnormal accumulation of glycosaminoglycans within cell lysosomes leading to a variety of signs and symptoms including alterations in speech and voice production. These changes were analysed in 44 patients with mucopolysaccharidosis (MPS) types I, II, and VI using standardized protocols. Compared to healthy individuals the diadochokinetic rate for the fast repetition of syllables was slower and more irregular, the voice-onset time for the voiceless consonant /p/ was shorter, and most patients had a hoarse voice. The fundamental frequency (F0) of sustained spoken vowels was in the normal range for most women and children with MPS, but adult males with MPS had a higher F0 than healthy men.