Fasting means stop of food and water intake for a period of time. Fasting is one of the causes of dehydration of the whole body. Dehydration is should be considered as a factor that may cause changes in vocal fold tissue rheology. This study was a prospective study on 70 volunteer's normal persons, 35 males and 35 females, with average age 29.7 years (28.5 years for females and 30.9 years for males). 4 volunteers with previous laryngeal symptoms and signs were excluded. The volunteers were tested when they were fasting and during non fasting period. Each person was asked about vocal symptoms and phonatory effort. Their voice was assisted as regard dysphonia, character of dysphonia, pitch, and loudness. Then each person underwent acoustic, aerodynamic, and videostroboscopic examinations. The results indicated that there is no subjective complaint of dysphonia or vocal effort. The fasting did not affect the stroboscopic finding, but there was affection of some parameters of acoustic and aerodynamic measures (as absolute jitter, amplitude perturbation quotient, and sound pressure level). The difference between fasting and non fasting show positive correlation with the duration of fasting but with no significant level except pitch perturbation quotient, mean flow rate, glottal resistance, and /z/ for female vowel.