There is paucity of data on the value of neovascular blood flow measurements in the differential diagnosis of human choroidal tumors, mainly due to difficulties in quantitating tumor vascularity in vivo. Color Doppler imaging and Duplex ultrasound, the combination of B-mode ultrasound and pulse Doppler analysis, were used to quantify tumor blood flow in 103 untreated tumors of the choroid. Pulsatile blood flow was detected at the tumor base of 62 choroidal melanomas (tumor height (TH) 3.1-11.7 mm) with a mean peak systolic frequency (MPSF) of 0.98 kHz (range 0.3-2.7 kHz). Compared to melanomas pulsatile neovascular flow in choroidal metastases (TH 2.1-6.5 mm, n = 12) was significantly higher (MPSF 1.87 kHz, range 0.8-3.5 kHz). No Doppler signals were elicited from age-related macular degeneration (n = 9), choroidal nevus (TH 1.5-2.1 mm, n = 18) and choroidal osteoma (n = 2). The results indicate that the quantitative measurement of tumor blood flow by duplex and color Doppler ultrasound may serve as a new diagnostic tool in the evaluation of intraocular tumors.