Abstract: Objective To investigate the role of ⁹⁹Tc^m-macroaggregated albumin (⁹⁹Tc^m-MAA)pulmonary perfusion imaging in evaluating thrombolytic therapy in pulmonary embolism. Methods Date of 54 patients with acut pulmonary embolism diagnosed by ⁹⁹Tc^m-MAA pulmonary perfusion imaging combined with radiography were analyzed retrospectively. Among them, pulmonary perfusion imaging was also performed one week after thrombolytic therapy. In some cases, pulmonary perfusion imaging was performed three months after thrombolytic therapy. Results The results of radiography were normal in all cases, among 347 abnormal pulmonary segments in 54 cases. 164 (47.3%) and 199 (57.4%) segments were restored to normal 1 week and 3 months later(χ²=10.68, P<0.05). Conclusion As a non-invasive diagnostic method,⁹⁹Tc^m-MAA pulmonary perfusion imaging play an important role in evaluating the therapeutic effectiveness of thrombolytic therapy in patients with pulmonary embolism.