This study was undertaken to determine the sensitivity and specificity of the transcranial Doppler (TCD) for diagnosis of vasospasm after rupture of anterior communicating artery (CoA) aneurysm. Results provided by 164 carotid angiograms and TCD measures were compared in 40 patients with CoA ruptured aneurysm. Twelve patients demonstrated a vasospasm on 22 angiographies. The distribution of angiographic vasospasm was 95.5% anterior cerebral artery (A1), 77.3% pericallosal artery (A2) and 59.1% middle cerebral artery (M1). A TCD velocity value equal or superior to 120 cm/sec was the criterion for TCD vasospasm on M1. The sensitivity of TCD on M1 for diagnosing vasospasm on M1 with high specificity (96.4%) was only 66.7%. A TCD velocity value equal or superior to 80 cm/sec, or superior to the homolateral TCD value on M1, was the criterion for TCD vasospasm on A1. The association of TCD criteria on A1 and M1 increased sensitivity to 83.3%, but specificity decreased to 75%. These results demonstrate that TCD is not yet efficient enough to diagnose vasospasm accurately when it is limited to A1. Moreover, the fact that vasospasm limited to A1-A2 was symptomatic in three patients suggests that angiography is still necessary to diagnose VS after CoA ruptured aneurysm.