A novel surface wave method is developed for non-invasively estimating viscoelasticity of tissues. In this method, a very small force is generated on the surface of tissue either by a mechanical shaker or the radiation force of ultrasound. The surface vibration of tissue is measured non-contact by laser or ultrasound. We have developed theory and techniques for measuring the surface wave for estimating the viscoelasticity of tissue. The surface wave speed can be measured by a phase change over distance method. The viscous properties of the tissue can be measured by the decay of surface wave amplitude with distance or wave dispersion. This method is especially useful for non-invasively measuring viscoelasticity of skin. According to our Institutional Review Board (IRB) application, “A Non-Invasive Technique for Measuring Skin Tissue’s Elasticity with Surface Wave Speed”, which was recently approved by Mayo Clinic, we are testing one or all of the following areas: dorsal forearm, back, abdomen, calf, thigh, and palm of hand.