Purpose: Determination of oxygen concentration in tissues affected by chronic venous insufficiency (CVI) has shown inconsistent results over the years and has confounded the pathophysiology of venous diseases. This study measured transcutaneous partial oxygen pressure (TcPO 2 ) levels in patients with CVI to assess oxygenation and variation in oxygenation according to CVI stage. Materials and Methods: A prospective study was performed on consecutive patients with unilateral CVI. TcPO 2 of diseased and unaffected limbs was measured in the supine and dependent positions. A single TcPO 2 value was measured at the site of greatest skin change or at the edge of the ulcer. The TcPO 2 values were analyzed and compared according to stage. Results: A total of 96 patients were included in the study with C4 (24.0%), C5 (19.8%), and C6 (56.3%) disease. The mean age was 44.7 years, and 85 (88.5%) were male. There was a statistically significant (P<0.01) difference in mean TcPO 2 levels between the unaffected limb (supine, 32.1 mmHg; dependent, 50.7 mmHg), C5 diseased limb (supine, 16.6 mmHg; dependent, 35.5 mmHg), and C6 diseased limb (supine, 24.2 mmHg; dependent, 40.4 mmHg). In the supine and dependent positions, the mean TcPO 2 in the affected limb was significantly lower (P<0.01) than that in the unaffected limb. Conclusion: TcPO 2 in advanced CVI can be used as a marker of oxygenation status. This is the first study in an Indian population looking at the relevance of TcPO 2 in the prognostication of advanced CVI.