Time-density curve study in contrast media transit has a theoretical possibility to evaluate asymmetric cerebral perfusion. We studied the right-to-left hemispheric difference of peak time in regional time-density curve. Twenty-seven chronic stroke patients underwent either dynamic CT or intravenous digital subtraction angiography (IVDSA), and single photon emission CT (SPECT). We placed symmetric regions of interest as appropriate in each study, and obtained a peak time of each regional time-density curve in IVDSA or dynamic CT, and a laterality index of reconstructed counts in SPECT. Right-to-left difference of peak time significantly correlated to the laterality index both in IVDSA and dynamic CT (r = -0.88, p < 0.001, and r = -0.82, p < 0.001, respectively). Thus, time-density curve study well reflected unilateral reduction of cerebral perfusion. Recent progress in acute thrombolytic intervention for ischemic stroke recommends a quick and efficient evaluation of ischemic status, and time-density curve study may satisfy this requirement.