Purpose: Differential diagnosis between arteriovenous (AVMs) and non-arteriovenous malformations (nAVMs) is important in patients with congenital vascular malformations, because AVMs can cause hemodynamic alteration and require immediate treatment. We investigated whether transarterial lung perfusion scintigraphy (TLPS) was useful for the diagnosis and post-therapeutic evaluation of AVMs in extremities. Materials and Methods: Fifty-seven patients (M:F=26:31, 21¡¾13 yr, 9 upper and 48 lower extremities) suspected of congenital vascular malformations in extremities underwent TLPS using ^99mTc-MAA before embolization/sclerotherapy. Dose-corrected shunt fraction (SF) was calculated from time-activity curve of the lung. Final diagnosis of AVMs was determined by angiography. In patients with AVMs, follow-up TLPS was done for post-therapeutic evaluation. Results: Sixteen patients (8 upper and 8 lower extremities) had AVMs, while the remaining 41 had nAVMs (1 upper and 40 lower extremities). The mean SF of AVMs on TLPS was significantly higher than that of nAVMs (66.4¡¾25.8% vs. 2.8¡¾ 4.3%, p=0.003). The sensitivity, specificity, and accuracy of TLPS (cut-off of SF = 20.0%) in diagnosis of AVMs before treatment were 93.8% (15/16), 100% (41/41) and 98.2% (56/57), respectively. The follow-up TLPS and angiography for post-therapeutic evaluation showed concordant results in 13 of 16 patients (81.3%) with AVMs. The mean SF of TLPS was significantly decreased after embolization/sclerotherapy (69.5¡¾24.0% vs. 41.0¡¾34.7%, p=0.01). Conclusion: TLPS provides hemodynamic information of AVMs in extremities semiquantitatively. Furthermore, the results of TLPS showed a high concordance rate with angiographic findings. Therefore, TLPS is useful for the diagnosis and post-therapeutic evaluation of AVMs in extremities. (Nucl Med Mol Imaging 2006;40(6):316-321)