Professional voice performance is strongly affected by the functional adjustments of the structures involved in voice production. Generally, these functional skills are required by means of intensive training. On the other hand, the individual morphology of the larynx and vocal tract limits this functional variability. Thus, to neglect morphological conditions might result in voice problems. The present paper summarizes investigations on the influence of morphological measurements on the voice classification of professional singers. Vocal fold length, vocal tract length and body height have been found to differ systematically between sopranos, mezzosopranos, altos, tenors, baritones and basses. Although the knowledge of morphological measures does not permit a definite assignment or prediction of the individual voice classification, the data are valuable for counseling by voice teachers and phoniatricians. This might contribute to the prevention of voice disorders.