BACKGROUND The diagnosis of hemangiomas and vascular malformations prior to interstitial laser therapy is principally based on clinical and B-mode ultrasonographic examination. Color-coded duplex ultrasonography provides additional information about the vascularization of these tumors. The aim of this study is to evaluate the benefit of this information for the diagnosis and treatment of hemangiomas. METHODS We examined 30 patients suffering from hemangiomas of various sizes and locations. A preliminary treatment plan was developed on the basis of B-mode ultrasonographic examination. This preliminary plan was either verified or changed after obtaining color-coded duplex ultrasonographic studies. RESULTS In comparison to B-mode ultrasonography, color-coded duplex ultrasonography allows clinically relevant classification of hemangiomas on the basis of their vascularization (no flow, palpation-induced flow, predominantly venous flow, predominantly arterial flow). In 53% of the cases, the preliminary therapeutic plan was modified partially or wholly on the basis of this additional information (new diagnosis, change in the planned surgical approach, and favoring other initial diagnostic and therapeutic options over laser therapy). CONCLUSIONS Color-coded duplex ultrasonography provides important additional information compared to B-mode ultrasonography and decisively influences hemangioma therapy. This imaging technique should be recommended for routine preoperative application in hemangiomas.