Differential diagnosis distinguishing between nonpuerperal mastitis and inflammatory cancer of the breast is difficult, the conventional method being mammography. In our study, we present the typical findings gained by sonography of 16 patients with nonpuerperal mastitis. They do not differ significantly from those cases with breast cancer. From these 16 patients, 7 were additionally examined using Colour and Pulsed Wave Doppler Sonography. International literature offers little practical knowledge in this field. In the immediate surroundings of the inflammation, we were able to represent up to four arterial vessels per patient. The parameters of the flow velocity wave form of these vessels were compared to those of the vessels in the correspondent quadrant of the contralateral breast. In all cases, the maximum systolic and the minimum end diastolic velocities were higher than in the contralateral breast, giving evidence of an increased vascularity. In 6 cases, the pulsatility and resistance indices in the inflammatory vessels were lower because of a decreased peripheral resistance of the vessel. Under therapy with antibiotics or Bromocriptine, these parameters were equalized in both breasts. The model of nonpuerperal mastitis shows, that Colour and Pulsed Wave Doppler Sonography makes it possible to differentiate tumours of the breast on the basis of an analysis of their vascularity and the comparison with the parameters of the vessels in the contralateral breast. The effects of a pharmacological therapy on the vascularity of breast tumours can also be measured with this method.