The present trial focused on the exact role of colour and power Doppler sonography in Achilles tendinopathy and correlated these techniques with the clinical severity of the disease and with findings on grey-scale sonography. Twenty patients with in total 28 symptomatic Achilles tendons were included in this prospective trial. Additionally included were the asymptomatic tendons (n = 12) of patients and both tendons (n = 30) of fifteen controls. The pain score of Robinson - which ranges from 0 (strong severe pain) to 100 (asymptomatic) - was used to assess clinical severity of the disease. Both tendons of patients and controls were examined by a GE LOGIQ 9 trade mark scanner with a small-parts 14 MHz transducer. Grey-scale sonography detected in total 31 focal hypoechoic areas in 19 (68 %) of the 28 symptomatic tendons. Colour as well as power Doppler sonography detected blood flow in 14 (74 %) of the 19 tendons with focal hypoechoic areas. No blood flow was detected in the remaining symptomatic tendons (n = 14) and in the asymptomatic tendons of patients or in both tendons of controls. Colour and power Doppler sonography resulted in a specificity of 100 % and a sensitivity of 50 % for symptomatic Achilles tendinopathy. Patients with blood flow within the tendon had a significantly lower score according to Robinson than symptomatic patients without flow (P = 0.009). It is concluded that colour and/or power Doppler sonography are useful as an adjunct to grey-scale sonography in the examination of Achilles tendinosis, especially because the presence of blood flow is associated with stronger pain, discomfort and physical restriction.