Maximum phonation time has been widely utilized as a simple clinical evaluation of the vocal function. Its importance has been emphasized by Van Riper (1954), Westlake and Rutherford (1961), Boone (1971), and other authors. A review of the literature revealed three trials of sustained phonation have been utilized by most researchers to determine maximum duration of phonation. Additionally, the review revealed a lack of test-retest reliability in maximum phonation time in children. The present study was designed to determine the variability in test-retest of maximum duration of· sustained /a/ among prepubescent male and female children. Eighty subjects, twenty at each of the four age levels, seven, eight, nine and ten, were selected from a larger pool using a random order table. Each age level was further divided into two groups of ten male and ten female subjects. A tape recording of twenty maximum phonations of /a/. was obtained for each subject. A second measure of maximum phonation time was recorded between two weeks and a month following the original run. The essential questions of this investigation were: 1. Given the means of age and sex groups of the longest performance of maximum duration of sustained /a/, is there a significant difference between runs one and two? 2. In the test cohort does the rank order of maximum phonation time differ between runs one and two? The following secondary questions were also posed: 1. Is there a significantly greater duration of the longest sustained /a/ when given twenty trials as opposed to the first three trials? 2. Is there a relationship between sex and the duration of sustained /a/? 3. Given four prepubescent age groups, is age a factor in relation to length of phonation?