We studied the effect of edema removal on transcutaneous oxygen tension (TcPO₂) in eight patients with leg ulcers. An external pneumatic compression device was effective in removing edema from the ulcerated limbs over a 5-day course of treatment, at which time all treated limbs were clinically free of edema. TcPO₂ levels at room air at the ulcer site were markedly reduced when compared with the control chest site, both before and after external pneumatic compression device therapy (p<0.001). Edema removal, however, did not significantly alter TcPO₂ values (p>0.9). No significant positional effects on TcPO₂ values were noted with patients supine, sitting, or with the affected limbs elevated. Five patients (63%) had increased TcPO₂ values adjacent to the ulcer site when receiving supplemental oxygen. For these patients, TcPO₂ values increased after oxygen inhalation, both before and after edema removal (p<0.05). We conclude that TcPO₂ values are markedly reduced in ulcerated edematous limbs. Edema, however, may not constitute a barrier to oxygen diffusion through the skin and does not account for the low TcPO₂ values in the ulcerated edematous limb. Therefore the positive therapeutic effect of removing edema is unlikely to be related to better oxygenation of the tissues.