The CT findings of the acute cerebral infarction are well known. However the CT findings of early stroke within 24 hours of the onset have not been sufficiently reported. The purpose of this study is to evaluate early acute cerebral infarction on CT within 24 hours after ictus. The early and accurate CT diagnosis could lead to the appropriate therapy and improved outcome of the patients. Authors retrospectively analyzed 16 patients with early acute cerebral infarction. Acute cerebral infarction was confirmed by follow-up CT in 11 patients, SPECT in 4 patients, and MRI in 1 patient. The CT findings of early acute cerebral infarction include effacement of cortical sulci or cistern (n=16, 100%), hyperattenuation of MCA (n=3), obscuration of lentiform nucleus (n=6), loss of insular ribbon (n=6) and subtle low density in hemisphere (n=5). The most frequent findings was effacement of cortical sulci in our study, and it was though to be the most important sign of early acute cerebral infarction.