The purpose of study was to investigate the impact of pre-surgical Infant Orthopaedics (IO) on consonant production at 18 months of age in children with Unilateral Cleft Lip and Palate (UCLP) and to compare the consonant production to that of age-matched children without clefts. The first ten children in a consecutive series of 20 with UCLP received IO and the following ten did not. Both groups had soft palate repair at 6.3 months of age. The cleft in the hard palate was unrepaired. Ten normally developing children without clefts served as controls. Nine children in each group accomplished the study. Phonetic transcriptions of consonants were made from audiotape recordings obtained during a 45-60 minute interactive session. No significant differences in the number of consonant tokens or of consonant types were found between the UCLP children with and without IO but both groups had significantly lower numbers than the control group. There was no significant difference in frequency of different manners or places of articulation of plosives between the UCLP groups. The frequency of occurrence of bilabial and dental consonant placements of plosives were significantly higher in the control group than in both UCLP groups.