Controlled laboratory experiments have been conducted to study the kinematics of wave-current interactions. The results confirm the conservation of waves under the steady state condition. The data also show that the kinematic effect of the current on waves can be treated as a simple Doppler shift. After the Doppler correction, the kinematics of the waves (either breaking or nonbreaking) follows the linear theory very well. The experiments also confirm the blockage of the waves by currents when the ratio u¿/C0 approaches -1/4. ¿ American Geophysical Union 1989