Dynamic optical coherence elastography, an emerging optical technique to measure material mechanical properties using the non-invasive imaging modality of optical coherence tomography is introduced. Dynamic mechanical excitations were applied to the samples while a spectral domain optical coherence tomography system was used for detection. Based on a simple mechanical model, material mechanical properties such as Young's moduli can be extracted from detected phaseresolved signals. Biological tissues and their biomechanical properties are currently the main objects for this technique due to its micron-scale resolution and relatively deep penetration. Quantitative results were achieved by this technique on tissue phantoms and rat tumor tissues. Different excitation approaches and applications for dynamic optical coherence elastography are also discussed.