This investigation was designed to assess the growth effect on the linear dimensions of human lips from childhood to adulthood. By means of serial computerized cephalometry, the changes in lip length and thickness were studied in 32 untreated male and female subjects from 8 to 18 years of age. It was observed that the maxillary and mandibular lips, under the influence of growth, increase in both dimensions with the advancement of age. During the period studied, the length and thickness of the lips of the male subjects exhibited greater increases both proportionally and numerically than the corresponding dimensions of female lips.