A pulsed Doppler flowmeter was used in a series of 352 consecutive patients undergoing isolated coronary artery bypass grafting. Doppler flow measurements were available on 909 single terminolateral bypass grafts (327 internal mammary arteries and 582 saphenous veins) and 58 sequential bypass grafts anastomosed to combinations of arteries. Flow (mL/min) categorized as a function of the recipient artery was distributed as follows: left anterior descending coronary artery, 69.9 +/- 2.5; right coronary artery, 68.0 +/- 5.0; diagonals, 61.0 +/- 4.1; obtuse marginals, 55.9 +/- 2.2; and posterior descending coronary artery, 53.3 +/- 3.0 (p < 0.001). Graft outflow obstruction resulting from torsion of the graft pedicle or anastomotic stricture was identified in 7 patients (2%). After graft revision, flow increased from 9 +/- 4 mL/min to 69 +/- 13 mL/min (p = 0.023), and velocity rose from 4.6 +/- 1.1 cm/s to 18.1 +/- 2.4 cm/s (p = 0.009). In conclusion, the system was adequate for operative use and allowed identification and correction of technical errors.