Forty-four intraocular mass lesions were studied using a new, non-invasive ultrasound technique known as color Doppler imaging (CDI). This technique displays color-encoded Doppler flow information throughout a two-dimensional gray scale image thus providing selective analysis of Doppler spectra in small vessels using pulsed Doppler. Abnormal Doppler shifts were demonstrated within 39 neoplastic lesions studied, but Doppler shifts could not be detected in three tumor-simulating lesions. In a group of 12 choroidal melanomas studied after radiation therapy, lower Doppler shifts were seen compared with a group of 28 tumors before therapy. This change in Doppler shift may reflect the decreased vascular supply of the tumor. Color Doppler imaging may be of value as an additional useful tool in the diagnosis and management of intraocular tumors.