The purpose of this study was to show whether color Doppler ultrasonography of the ovarian arteries is a useful tool for the differential diagnosis of pelvic inflammatory disease (PID) and appendicitis. The study included 50 female patients with clinical symptoms of acute pelvic inflammation and 50 healthy women of the same age as a control group. All were examined with color Doppler ultrasonography to visualize the internal genitalia and estimate the blood flow through the ovarian arteries. Peak systolic velocity (PSV), end diastolic velocity, pulsatility index (DPI), and resistance index were measured. In the healthy women, ovaries were normal in size, and the parameters of ovarian arterial flow were PSV 0.30-0.50, systolic/diastolic ratio <0.7, DPI 1.23-1.50. In 45 of the patients, there was infection and enlargement of the ovaries and/or salpinx, and flow parameters were PSV 0.40-0.70, systolic/diastolic ratio 0.5-0.8, and DPI 1.40-1.96. In five cases the ultrasound image was obscure, and flow parameters were similar to those of healthy women. These patients underwent surgery for a diagnosis of appendicitis. Our study showed that in cases of diagnostic differentiation between PID and appendicitis, examination with color Doppler ultrasound is very easy and useful. The relatively increased flow parameters in ovarian arteries direct the diagnosis to PID.