Relationships between the degree of lesion and that of vocal dysfunction were investigated in 122 cases of vocal fold polyp. A normalized size of polyps and glottic gap were correlated to the results of phonatory ability tests, stroboscopic investigations, acoustic analyses, and perceptual evaluations. There was no significant correlation between the size and the gap. The size of polyp was negatively correlated to fundamental frequency, whereas it was positively correlated to roughness of voice, assymmetry of vocal fold vibration, irregularity of vocal fold vibration, pitch perturbation quotient, amplitude perturbation quotient, and normalized noise energy. The glottic gap showed negative correlations to maximum phonation time and sound pressure level, and positive correlations to mean airflow rate and fundamental frequency.