The BA-101 Body Composition Analyzer provides values for percent fat, percent and total body water, percent lean body weight, and the lean to fat ratio. In 16 healthy adult male subjects, the volume of distribution of theophylline was found to be strongly correlated with the lean/fat ratio (r = .767) and to the percent fat (r = (-)0.79). Knowledge of body composition, however, did not allow for a more accurate prediction of a starter dose of theophylline.