The aim of our study was to clarify possible differential color Doppler US features between parathyroid lesions and other cervical masses. A total of 56 parathyroid lesions in 54 patients with primary hyperparathyroidism were preoperatively examined with color Doppler sonography. Color Doppler flow patterns were compared with those of 72 thyroid nodules and 20 cervical lymph nodes. In 38 parathyroid lesions a correlation between color Doppler patterns and size, location, and pathological findings was performed. Color Doppler sonography showed five vascular distribution patterns: pattern I, absence of flow; pattern II, focal peripheral flow ("vascular pole") with arterial Doppler spectrum; pattern III, peripheral flow; pattern IV, internal flow ("parenchymal pattern"); pattern V, peripheral and intranodular flow. Pattern I was not specific for any cervical lesion considered. Conversely, pattern IV was observed solely in parathyroid lesions, and pattern II was observed in only one nonparathyroid lesion (thyroid nodule). Mixed pattern (pattern V) was observed solely in thyroid nodules. In addition, pattern III was a characteristic finding of thyroid nodules and was observed in only one parathyroid lesion. Color Doppler patterns of the parathyroid masses did not correlate with the size of the lesion or pathological findings, but only with the location of the gland. Our study showed that color Doppler assessment of parathyroid lesions is a useful integration of gray-scale US and may be helpful in distinguishing parathyroid lesions from other cervical masses.