Twenty-one tumors in 20 children were evaluated with duplex and color Doppler imaging to determine the value of the technique in assessing the origin and pattern of vascular supply and the degree of neovascularity. The origin of the vascular supply was detected correctly in 12 of 13 tumors that were subsequently resected. In five children, this aided in determining the organ from which the tumor originated, and in one child, it established the presence of a tumor by showing blood flow in the center of a suspected abscess. In 18 tumors, color Doppler imaging showed the pattern of the vascular supply. Eleven had a peripheral pattern, and seven had a central, branching pattern. Although individual tumor types appeared to have characteristic patterns of vascular supply, these were not specific enough to aid in making a specific diagnosis. When the degree of intratumor neovascularity was graded on the basis of the findings on color Doppler imaging, it agreed with the results of histologic evaluation in 16 of 19 tumors. In one tumor, neovascularity was overestimated, and in two, it was markedly underestimated. Our experience suggests that color Doppler imaging is useful in detecting the origin and pattern of vascular supply and the degree of intratumoral blood flow in a variety of solid tumors in children.