The number of dermatologic entities that can be studied by ultrasound examination (US) of the skin is increasing. Conventional US and high frequency US (HFUS) are considered useful additional tools in improving the diagnosis and management of common benign and malignant skin tumors. US may help in positive and differential diagnosis of primary melanocytic neoplasms and of locoregional spread in melanoma patients. US preoperative evaluation of primary melanoma thickness correlates with histologically estimated melanoma thickness, and can help determine surgical margins and indications for sentinel lymph node biopsy. It is also useful during follow-up after surgical treatment for early detection of recurrence or metastases. In this case report, we present two cases of skin lesions clinically suspicious for malignancy. The first lesion was a round nodule 3 mm in diameter, resembling a blue nevus. In HFUS it was well delimited, hypoechoic, and well vascularized. The second lesion presented as an elevated, well-circumscribed nodule, 5-6 mm in diameter, inhomogeneous in color. HFUS depicted a poorly delimited, irregular, hypoechoic lesion crossing the dermoepidermal junction. At the first exam it was not vascularized, but 6 months later a number of vascular flow signals within the lesion were found. In histopathological examination the lesions were finally diagnosed as, respectively: benign cavernous hemangioma and melanoma. In both presented cases HFUS proved to be useful in a differential diagnosis of suspicious skin lesions. Noninvasive and easy to perform, HFUS is a valuable diagnostic method in dermatology.