Single-photon emission computed tomography (SPECT) and transcranial Doppler (TCD) ultrasound are of good prognostic value in acute stroke, and combined they may be an accurate way to determine a target group of patients with maximum therapeutic response. Seventy consecutive patients were studied (42 with middle cerebral artery strokes, 18 with transient ischemic attacks {TIAs}; 10 were excluded due to failure of insonation). Two SPECT studies were performed at 2.1 +/- 1.2 and 13.8 +/- 3.1 days after onset. Serial TCD studies were done at 10 hours and at the time of the SPECT studies. Neurological deficit was scored on admission and 2 weeks later (using the Canadian Neurological Scale). Cerebral perfusion index (CPI) was derived by multiplying the values for TCD and SPECT patterns. Positive correlation was obtained in all 16 patients in whom cerebral angiography was performed within the first 3 days after onset. The occlusive TCD pattern and absence of perfusion on SPECT were common in the stroke group (19/42 patients) and were never seen in those with TIAs. A normal TCD pattern and normal perfusion on SPECT were more common in the patients with TIAs (9/18 vs 8/42, p = 0.02; 5/10 vs 1/40, p = 0.0003). The occlusive TCD and SPECT patterns were associated with the highest mean infarction volume (147 +/- 87 vs 19 +/- 21, p less than 0.0001) and all nonocclusive TCD and SPECT patterns were associated with the better short-term outcome (43.2 +/- 33.9 vs 92.4 +/- 20.2, p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)