Background: Vascular tumor is a specific entity of vascular anomalies with variable clinical manifestations and outcomes. Although surgical intervention is the gold standard to establish diagnosis and treatment, the procedure also carries certain risk especially in cases with large and inoperable tumors. Determinant factors to predict clinical outcomes among those patients were not well studied. The study aimed to explore clinical characteristics including investigational and treatment approaches as well as associated prognostic factors of vascular tumors specifically in pediatric populations. Methods: Pediatric patients with confirmed diagnosis of vascular tumors between January 1, 2005 and December 31, 2017 were enrolled in this study. Clinical data including initial clinical manifestations with associated complications, diagnostic studies used to establish diagnosis, treatment modalities provided and final outcomes were retrospectively reviewed and analyzed. Results: In all, 50 patients with confirmed diagnosis of vascular tumors were enrolled. The median age at diagnosis was 11.5 years with equal gender distribution. The most common type of vascular tumors was hemangioma (n=41, 82%), followed by pyogenic granuloma (n=4, 8%), kapasiform hemangioendothelioma with Kasabach-Merritt phenomenon (n=2, 4%), infantile hepatic hemangioma (n=2, 4%) and juvenile nasal angiofibroma (n=1, 2%). The median age at diagnosis among patients with cutaneous vascular tumors (12.4 years) was significantly older than the age of those with visceral vascular tumors (1.3 years) with p-value of 0.009. The mean size among patients with visceral tumors (7.46±4.84 cms) was significantly greater than the size among patients with cutaneous tumors (3.21±3.7 cms) with p-value of 0.023. Size of the tumor was the only independent risk factor associated with clinical outcomes.Conclusion: Clinical characteristics of vascular tumors are heterogenous. Diagnosis can be made using clinical manifestations combined with radiological and histopathological examination. Treatment approaches consist of close observation, medications and surgery. Clinical outcomes are favorable among most patients and size of the tumor is an independent risk factor associated with outcomes. This study was registered at www.clinicaltrials.in.th under the title, “Vascular tumors in pediatric hematology-oncology settings” with registration number: TCTR20190917001.