In a prospective study, 55 patients were examined by transcranial duplex sonography (TCCS) after subarachnoid hemorrhage (SAH) to determine whether additional transcranial duplex examination on the middle cerebral artery M2 segments would aid in the examination of the MCA stem segment. The mean blood flow velocities and pulsatility index were correlated to the occurrence of delayed ischemic neurologic deficits (DIND). Out of 47 patients included, 21 did not experience any delayed deficit (group I), 15 did (group II), and in 11 the extent to which vasospasm contributed to a neurologic deficit was unclear (group III). The highest blood flow velocity and the greatest increase of mean blood flow velocity on 1 day were significantly higher in groups II and III both in M1 and in M2. In 10 patients in group II, where the onset day of DIND was known exactly, Doppler data indicating ischemia before or at the time of DIND were observed in nine. In eight patients, Doppler of the MCA stem alone would have provided enough information to recognize the risk of symptomatic vasospasm; in one patient, only the M2 Doppler gave an indication of ischemic complication. Transcranial duplex sonography may provide additional information to TCD by accurate delineation of M1/M2 vasospasm and therefore may help plan cerebral angiography and neurointerventional treatment.