Objective: Vascular anomalies are a diagnostic and therapeutic challenge. Errors in diagnosis lead to treatment delay, inappropriate interventions and prolonged suffering. The aim of this study was to analyze patterns of misdiagnosis among patients referred to a vascular anomalies center (VAC). This will better define the problem and may be used to refine and improve referral guidelines for patients with vascular anomalies. Patients and Methods: After IRB approval, we performed a single-center retrospective review of all patients referred to a vascular anomaly between January 1, 2008 and December 15, 2011. Evaluation of both referral and final diagnosis was made. Data regarding accuracy of diagnosis were determined and compared for both vascular tumors and malformations. Results: Mean age was 7.9 ± 7.7 (13 days - 66 years). 42% had a correct diagnosis at the time of referral. Vascular tumors were correctly diagnosed more often than vascular malformations (58% vs 38%). The most common misdiagnosis for infantile hemangioma (IH) was venous malformation (VM). The most common misdiagnosis for VM was IH. Nonspecific and historical terms such as “mass”, “lymphangioma”, and “cavernous hemangioma” frequently appear as the referral diagnosis. Conclusion: Referral misdiagnosis is common. IH and VM are frequently confused and if there is any uncertainty in the diagnosis, these patients should also be referred to a VAC, in addition to the more complicated anomalies. Outdated nomenclature remains prevalent and continued efforts should be made to adhere to International Society for the Study of Vascular Anomalies (ISSVA) classification. Improvements in diagnostic accuracy are likely to greatly improve patients’ care.