Background and Purpose-It remains uncertain whether lower dose intravenous tissue-type plasminogen activator (tPA) for stroke is as effective and safe as the standard dose. Methods-We analyzed data from the Thrombolysis Implementation and Monitor of Acute Ischemic Stroke in China (TIMS-China). Patients who were treated within 4.5 hours after symptom onset were included. These patients were divided into 5 groups according to tPA doses given: < 0.5, 0.5 to 0.7, 0.7 to 0.85, 0.85 to 0.95, and >= 0.95 mg/kg. Symptomatic intracranial hemorrhage, mortality, and 90-day outcome assessed by modified Rankin scale were analyzed. Results-A total of 919 patients were enrolled. Among them, 9 had < 0.5 mg/kg, 75 had 0.5 to 0.7 mg/kg, 131 had 0.7 to 0.85 mg/kg, 678 had 0.85 to 0.95 mg/kg, and 26 had >= 0.95 mg/kg. Because of sample sizes, only 0.5 to 0.7, 0.7 to 0.85, and 0.85 to 0.95 mg/kg groups were compared. Median tPA doses were 0.64, 0.79, and 0.90 mg, respectively. After adjustment for the baseline variables, there were no significant differences in mortality(5.41% versus 8.66% versus 7.36%; P= 0.695) and symptomatic intracranial hemorrhage (0% versus 3.82% versus 1.46%; P= 0.106). The 0.5 to 0.7 mg/kg group had less excellent recovery outcome (modified Rankin scale, 0-1) than 0.85 to 0.95 mg/kg group (41.89% versus 53.83%; odds ratio= 0.58; P= 0.031) at 90 days. The 0.70 to 0.85 mg/kg group had less functional independence outcome (modified Rankin scale, 0-2) than 0.85 to 0.95 mg/kg group (54.33% versus 64.51%; odds ratio= 0.66; P= 0.036) at 90 days. Conclusions-Our study suggests that standard-dose intravenous tPA for stroke had more favorable outcome without increasing the risk of symptomatic intracranial hemorrhage than low-dose tPA. For Asian people, 0.9 mg/kg should be the optimal dose of tPA to treat acute ischemic stroke.