Four patients who were evaluated for hypersomnia-sleep apnea syndrome were found in all-night sleep studies to have obstructive or mixed apneas related to their sleeping positions. All four were available for comprehensive follow-up and were subsequently restudied while avoiding the supine position. Supine, prone, and lateral decubitus apnea indices were calculated for each patient for each night. The supine sleeping position was associated with significantly more apneas than the non-supine positions. Keeping these patients off their backs when they slept was effective treatment. Additionally, when results of surgical or pharmacologic treatments of apnea are evaluated, positional apnea indices should be considered.