An advanced in-vivo imaging technology; namely, combined ultrasound, elasticity and photoacoustic imaging, capable of visualizing both structural and functional properties of living tissue, is presented. This hybrid imaging technology is based on the fusion of the complementary imaging modalities and takes full advantage of the many synergistic features of these systems. To highlight fundamental differences and similarities between the imaging systems and to appreciate advantages and limitations of each imaging system, the basic physics of each imaging system is described. The experimental aspects of combined imaging including hardware, signal and image processing algorithms, etc. are presented. Noise and primary artifacts associated with each imaging modality and combined imaging system are analyzed, and techniques to increase and optimize contrast-to-noise and signal-to-noise ratios in the images are discussed. Finally, biomedical and clinical applications of the combined ultrasound, elasticity and photoacoustic imaging ranging from macroscopic to microscopic imaging of pathology are demonstrated and discussed.