This study compared transcranial Doppler (TCD) imaging and outcomes of carotid angioplasty and stenting (CAS) in stenosis after carotid endarterectomy (CEA) vs primary atherosclerotic stenoses. A prospectively accumulated database of 812 CAS procedures was analyzed retrospectively. Two groups were created. Group 1 had 72 restenoses at a mean of 71 months (range, 5-245 months) after initial CEA. Group 2 had 740 primary stenoses. Clinical end points were cerebral ischemic events and death. TCD end points were numbers of isolated microemboli and microembolic showers during five procedural phases. Groups 1 and 2 were evenly matched for demographic data: median age, 70 vs 71 years; 44 (61%) vs 525 men (71%); 14 (19%) vs 147 symptomatic (20%). Seven (0.9%) deaths and 10 major (1.2%) and 21 minor (2.6%) strokes occurred in group 2 (P = .049). Mean (standard deviation) numbers of isolated microemboli for groups 1 vs 2 were wiring, 37.0 (31.1) vs 50.4 (52.6); predilation, 14.8 (18.7) vs 21.7 (21.8); stent placement, 58.6 (31.1) vs 64.7 (38.8); postdilation, 20.4 (16.5) vs 27.2 (34.9), cerebral protection device (CPD) use, 44.2 (30.2) vs 37.5 (36.8); total, 134.8 (68.7) vs 175.3 (113.8). Microembolic showers: wiring, 1.7 (4.5) vs 2.2 (6.4); predilation, 2.1 (4.1) vs 3.3 (5.8); stent placement, 21.5 (22.0) vs 26.9 (25.1); postdilation, 5.3 (15.7) vs 5.0 (8.1); CPD use, 5.8 (6.9) vs 6.2 (8.9); total, 30.4 (36.0) vs 39.6 (35.0). TCD data for CPD use vs without for isolated emboli: wiring, 53.2 (45.1) vs 44.3 (51.7); predilation, 24.7 (20.2) vs 18.2 (22.5); stent placement, 77.5 (34.8) vs 53.5 (37.3); postdilation, 33.6 (36.6) vs 20.7 (21.8); CPD use, 38.3 (36.6) vs 0; total, 222.5 (113.8) vs 132.3 (89.1). Showers: wiring, 2.4 (6.6) vs 1.9 (5.8); predilation, 4.2 (6.4) vs 2.4 (5.0); stent placement, 38.9 (25.8) vs 16.2 (18.7); post-dilation, 7.0 (11.2) vs 3.4 (6.4); CPD use, 6.3 (8.9) vs 0; total, 58.4 (37.7) vs 23.3 (23.1). P = .01 for showers during wiring and P < .001 for all other variables. After correction for the difference in CPD use between groups 1 and 2 (17 out of 72 [24%] vs 369 out of 740 [50%]), no statistically significant differences remained in numbers of isolated emboli and embolic showers in the procedural phases or for the entire procedure. No statistically significant differences were found when TCD-detected microembolic load for early (<3 years between CEA and CAS) and late (>5 years) restenoses were compared. CAS for restenosis after CEA has a complication rate lower than primary CAS. The time interval between CEA and CAS did not influence micro embolic load.