Background and Objectives : Vocal fold cyst is generally treated by surgical resection, it has a difference with vocal fold polyp, treated by conservative management first. Decrease in mucosal waves is known as main diagnostic criteria of vocal fold cyst. Sometimes there is a difficulty for diffrential diagnosis between cyst and polyp only by endoscopic examination. The purpose of the study is to identify the objective features of vocal cyst and polyp on the basis of voice analysis for the proper differential diagnosis, especially at high pitched phonation. Materials and Method : The voice analysis was done in 15 focal fold cyst patients and 42 vocal fold polyp. Parameters of perceptual assessment, acoustic and aerodynamic measure, and voice range profile were compared between two groups. Results : Vocal fold cyst patients showed significantly reduced MPT by acoustic and aerodynamic analysis, narrowed frequency-range and low maximun frequency by voice range profile analysis compared with vocal fold polyp patient. Maximun frequency 381 Hz is established for cut off value, differential diagnosis between cyst and polyp (ROC analysis, sensitivity 60%, specificity 68%). Conclusion : Voice analysis is helpful for differential diagnosis between vocal fold cyst and polyp, especially there is a difficulty for distinguish cyst from polyp at clinical situation by endoscopic examination. The result of decreased maximum frequncy at vocal fold cyst supports incomplete high-pitched phonation and falsetto regester at vocal fold cyst patients due to decreased mucosal wave, compared with vocal fold polyp patients.