Introduction/objective: To determine the value of power Doppler (PD) ultrasonography (US) and contrast-enhanced power Doppler (CEPD) US in the diagnosis of acute appendicitis and the prediction of histopathologic stages. Methods and material: 50 patients with suspected acute appendicitis were evaluated by the same radiologist with PD US and CEPD US. Air micro bubbles stabilized by a granulate of "galactose and palmitic acid" were used as a contrast medium for sonography with the concentration of 400 mg/ml. PD US and CEPD US results were later correlated with the surgical and histopathologic findings. PD US and CEPD US findings were considered positive for appendicitis; if there was depiction of hyperemia in the wall of the appendix or if there was depiction of prominent peripheral vascularity when compared with normal soft tissues; and negative if both hyperemia and peripheral hyperemia were not prominent. Results and discussions: Of the 50 patients, 35 patients had histopathologically proven acute appendicitis. CEPD US showed prominent hyperemia in the appendiceal vessels or feeding vessels of the inflamed appendix, and resistance index (RI) calculations were easier. There was statistically significant difference between mean RI values of the normal appendix, suppurative appendicitis and gangrenous appendicitis. PD US has accuracy of 80%, sensitivity of 74% and CEPD US has 98%, and 100% in the diagnosis of acute appendicitis. CEPD US identified 100% of suppurative appendicitis and gangrenous appendicitis. Conclusion: CEPD US is a promising method in the diagnosis of acute appendicitis and determination of the inflammation stage. © 2003 Elsevier Ireland Ltd. All rights reserved.