The purpose of this study was to evaluate the outcome regarding speech intelligibility, articulation, nasalance, nasality and voice in adult cleft palate patients. An additional objective of this study was to delineate the impact of a unilateral versus bilateral cleft lip and palate on speech outcome and to compare the nasalance and nasality patterns of cleft palate adults with data from non-cleft subjects. Objective (nasalance values obtained by the Nasometer, mirror-fogging test according to Glatzel and the determination of the dysphonia severity index, DSI) and subjective assessment techniques (perceptual evaluation of speech, nasality and voice, the Bzoch tests and the Gutzmann test) were used. All 14 subjects with a complete unilateral or bilateral cleft lip and palate consulted the same craniofacial team, followed an identical surgical protocol, completed the surgical cleft palate treatments and followed speech therapy. Most of the patients had a fairly satisfactory outcome with normal speech intelligibility, but three types of articulation errors seemed to predominate. More than one half of the subjects demonstrated hypernasality. In comparison with the non-cleft normative data, statistically higher nasalance values were obtained in the cleft group. The subjects had a DSI score that corresponds with a normal or slightly impaired voice quality. No significant differences regarding speech outcome were found between subjects with a unilateral or bilateral cleft lip and palate. The results provide important information for speech-language pathologists to evaluate and improve speech outcome in cleft palate patients.