Purpose: Childhood Apraxia of Speech (CAS) is a developmental disorder affecting the speech motor programming and planning. This study aims to investigate deviant vowel and diphthong articulations of German children with suspected CAS. Methods and Data: A corpus of 115 isolated stimulus words were evoked by picture naming, 33 pseudo words were evoked by repetition and collected for three German children with suspected CAS aged 5;9 to 6;3 years and for 21 controls. Perceptual and acoustic analysis were done in order to judge the vowels and diphthong realisations of suspected CAS-children vs. control speakers. Results: The perceptual evaluation shows vowel and diphthong errors in the suspected CAS-children in contrast to the controls. Discussion: This study shows that incorrect vowel and diphthong productions can be detected in children with suspected CAS by perceptual and acoustic evaluation.