We evaluated the efficacy of contrast-enhanced color Doppler ultrasonography with a galactose-based echo contrast agent, Levovist, for the diagnosis of renal mass lesions. The final pathologic diagnosis of eight renal mass lesions was renal cell carcinoma in 6 patients, transitional cell carcinoma in 1 patient and renal cyst in 1 patient (age range, 47 to 77 years; mean, 59.1). Especially in patients with renal cell carcinoma, contrast-enhanced color Doppler ultrasonography showed enhancement of mass lesion blood flow signal intensities. In all patients, contrast enhancement was demonstrated. Diagnostic capacity was improved in all patients, excluding 2 in whom mass lesion blood flow was detected by plain color Doppler ultrasonography. Furthermore, in patients with transitional cell carcinoma, the hemodynamics of mass lesions could be visualized, and diagnostic capacity was high. Contrast-enhanced color Doppler ultrasonography with Levovist, showed markedly higher mass lesion blood flow than that obtained by the plain color Doppler procedure, improving diagnostic capacity. This procedure was useful for diagnosing renal mass lesions.