With the use of the pharyngoesophageal (PE) segment as the neoglottis in esophageal speakers, their voice quality becomes significantly different from that of laryngeal speakers. The present study investigated the characteristics of the vocal tract resonance in Mandarin esophageal speakers. The first three formant frequencies of vowels /a, epsilon, i, [see in text], u, y/ produced by seven superior esophageal and seven laryngeal speakers of Mandarin were obtained. For each formant, the formant frequencies measured from the medial 80% of the vowel portion were averaged, and data obtained from esophageal speakers were compared with that obtained from laryngeal speakers. The results indicated that esophageal speakers were associated with significantly higher formant frequencies (F(1), F(2), and F(3)) and a significantly diminished vowel space circumscribed by the three corner vowels /i/, /a/, and /u/ when compared with laryngeal speakers. The findings that formant frequency changes across vowels were systematic and similar for esophageal and laryngeal speakers are consistent with those previously reported in English. It can be concluded that vocal tract transmission has been changed in esophageal speakers of Mandarin after laryngectomy.