New ultrasound techniques for blood flow estimation have been investigated in-vivo. These are vector velocity estimators (Transverse Oscillation, Synthetic Transmit Aperture, Directional Beamforming and Plane Wave Excitation) and adaptive spectral estimators (Blood spectral Power Capon and Blood Amplitude and Phase Estimation). It was shown that the vector velocity estimators can provide reliable angle independent estimates and new insight to the complexity of blood flow, and that adaptive spectral estimators can produce useful spectrograms faster than the conventional spectral Doppler method.