PURPOSE: To compare power Doppler ultrasound (PDUS) and color Doppler ultrasound (CDUS) in the depiction of vascularity of solid breast nodules and to differentiate the lesions on the basis of the distribution and amount of vascularity. MATERIALS AND METHODS: Sixty biopsy-proven solid breast masses (benign: 26, malignant: 34) evaluated with PDUS and CDUS using 5-10MHz transducer. The setting included depth of 40mm, 6cm/sec of scale, 700Hz of PRF. A color gain range was 46-78% (mean: 66%) in CDUS and 62-96% (mean: 77%) in PDUS. We compared the vascularity on CDUS and PDUS and decided which modality depicted more Doppler signals. The amount of vascularity was categorized as absent, minimal and marked. The pattern of vascularity was classified -as central, peripheral and mixed. RESULTS: PDUS depicted more Doppler signals in 27 and equal in 33 lesions (p< 0.01). Of the 26 benign nodules, 2 showed absent flow, 14 had minimal flow and 10 had marked flow. Of the 34 malignant nodules, 4 had absent flow, 14 had minimal flow and 16 had marked flow (p0.05). Among the nodules which depicted vascularity in PDUS (benign: 24, malignant: 30), benign nodules showed central in 5, peripheral in 14, mixed in 5 and malignant nodules central in 10, peripheral in 16, mixed in 4 (p w 0,05). CQNCLlSIQN: PDUS is more sensitive than CDUS in the depiction of the vascularity of solid breast masses. However, the amount and distribution of vascularity in solid breast masses at PDUS are nonspecific in the differentiation of solid breast masses.