AcoustoÑphotonic imaging (API) , combines the technique of diffusiveÑphotonÑdensityÑ wave (DPDW) imaging with ultrasound modulation of light in a new mode of medical imaging which promises improved resolution, accuracy, and penetration. Analytical results reported previously showed that a focussed ultrasound beam at one frequency, mixing with a diffusive wave at another, produces signals at the sum and difference frequencies, and that these signals originate near the ultrasound focus. In heterogeneous tissue, reconstruction from DPDW images is difficult because the problem is underÑdetermined and illÑposed, because practical considerations constrain probe locations, and because probe placement and orientation are susceptible to motion. API provides additional data in several ways: First scanning the ultrasound focus throughout the sample volume and measuring the mixing signals images three-dimensional structures with contrasting optical or ultrasound properties. Secondly, the ultrasound focus acts as a "virtual" DPDW source which can be located deep inside the tissue without invasive probe placement . Surface detectors and deep virtual sources provide the equivalent of transillumination imaging. Diffusive imaging using transillumination and reflection together offers significant improvements in resolution and accuracy over that using either alone. Finally, sampling a few locations with the ultrasound focus, perhaps aided by ultrasound imagery, may to correct for probe motion. In summary, API combines DPDW and ultrasound imaging, retaining the best features of both.