OBJECTIVE Air plethysmography has been useful in assessing patients who have chronic venous insufficiency. Limb reflux times determined by color-flow-assisted duplex scanning have been shown to correlate with the severity of chronic venous insufficiency. The purpose of this study was to compare air plethysmographic measurements with reflux times obtained by color-flow-assisted duplex scanning in patients with chronic venous insufficiency. METHODS One hundred twenty-two limbs in 61 consecutive patients with various stages of chronic venous insufficiency were evaluated; air plethysmographic and color-flow-assisted duplex scans were performed at the same sitting. Fifty-nine of the patients had venous ulceration. Values obtained by air plethysmographic scans included venous filling index, ejection volume, residual volume, ejection fraction, and residual volume fraction. Color-flow-assisted duplex scan values included reflux times in the deep and superficial venous segments and total and mean limb reflux times. RESULTS Using the Pearson correlation, the venous filling index was found to correlate significantly with total limb venous reflux times, mean total limb reflux times, and venous reflux times in the deep venous system, as determined by color-flow-assisted duplex scans (p < 0.001). CONCLUSIONS Limb reflux time as determined by color-flow-assisted duplex scans correlated significantly with the air plethysmographic variable accepted as a measure of the severity of venous reflux, the venous filling index. This study confirms the validity of total limb reflux times in the quantification of chronic venous insufficiency.