BACKGROUND: vocal features of monozygotic twins and their relation with the normative data for unrelated peers. PROCEDURES: the sample was composed of two pairs of adult twins, one pair of each gender had undergone otorhinolaryngologic, auditive, vocal auditory perceptual and acoustic evaluations. Data was showed in a descriptive way and discussed comparatively with the normative data for unrelated peers on literature and on the applied program. The test t of Student (significance 5%) was used to test the differences between the average and the normative values. RESULTS: there were no differences related to voice onset, articulation, loudness, resonance, breathing type and mode in both evaluated monozygotic twin pairs, and they were adequate. There were signs of muscular hypertension related to vocal production in both pairs, the type of voice was considered slightly altered in both pairs and there was a difference regarding the twin's Maximum Phonation Time. All the acoustic measurements were in accordance to the normative patterns of Multi Dimensional Vocal Program. CONCLUSION: the measurements found in this study seem to follow the trend of those described in studies that evaluated monozygotic twins.