With increasing demand for in-vivo observation of living cells, microscope techniques that do not need staining become more and more important. In this talk we present a combined multi-photon-acoustic microscope with the possibility to measure synchronously properties addressed by ultrasound and two-photon fluorescence. Ultrasound probes the local mechanical properties of a cell, while the high resolution image of the two-photon fluorescence delivers insight in cell morphology and activity. In the acoustic part of the microscope an ultrasound wave, with a frequency of GHz, is focused by an acoustic sapphire lens and detected by a piezo electric transducer assembled to the lens. The achieved lateral resolution is in the range of 1&mgr;m. Contrast in the images arises mainly from the local absorption of sound in the cells, related to properties, such as mass density, stiffness and viscose damping. Additionally acoustic microscopy can access the cell shape and the state of the cell membrane as it is a intrinsic volume scanning technique.The optical part bases on the emission of fluorescent biomolecules naturally present in cells (e.g. NAD(P)H, protophorphyrin IX, lipofuscin, melanin). The nonlinear effect of two-photon absorption provides a high lateral and axial resolution without the need of confocal detection. In addition, in the near-IR cell damages are drastically reduced in comparison to direct excitation in the visible or UV. Both methods can be considered as minimal invasive, as they relay on intrinsic contrast mechanisms and dispense with the need of staining. First results on living cells are presented and discussed.