Adaptive volume rendering is provided for medical diagnostic ultrasound. The opacity of B-mode data is set relative to the opacity of Doppler data. The opacities for the different types of data are set as a function of ray depth. For example, the opacity of B-mode data near a tissue border is set to be more opaque than for tissue away from the border, and the opacity for flow data near a flow border is set to be less opaque than for flow away from the border. An image is rendered using a rendering parameter set as a function of ray depth, B-mode information and Doppler information. Other processes for enhancing and/or using rendering may be used.