To investigate whether the noninvasive determination of transcutaneous oxygen tension (TcO2) can be used to evaluate the degree of hemiplegia, we measured TcO2 before and after a 2-mo rehabilitation course in 12 patients with hemiplegia caused by cerebrovascular diseases. All patients with no evidence of heart failure (ejection fraction evaluated by echocardiogram: 68.7 +/- 6.4%) began to receive conventional physical therapy a few days after the onset of stroke. The measurement of TcO2 was performed at 9:00 a.m. with an electrode placed on the skin surface of the flexion side of the forearm 5 cm distal to the elbow. Before rehabilitation, the difference in TcO2 between the paralyzed and healthy upper limbs ((delta)TcO2) in patients at Brunnstrom's stage V was significantly lower than that in patients at stages II, III, and IV (P < 0.05, P <0.01, and P < 0.01, respectively). After rehabilitation, (delta)TcO2 in patients at Brunnstrom's stage V was significantly lower than that in patients at stage III(P < 0.05). The (delta)TcO2 in the patients with severe hemiplegia was larger than that in patients with slight hemiplegia. In addition, TcO2 at the paralyzed upper limb increased significantly after rehabilitation (before 62.7 +/- 10.5 mm Hg; after 71.9 +/- 9.0 mm Hg; P < 0.05), although arterial blood oxygen tension (PaO2) did not. Therefore, the TcO2 determination may be useful in assessing the degree of hemiplegia in upper limbs.