To overcome the limitation in imaging depth that restricted conventional techniques to shallow tissue layer or to thin sample slices, multiphoton microscopy has been implemented as a label-free solution for deep-tissue analysis. The simultaneous interaction of two or more photons with the tissues enables to address electronic states of a molecular target via harmonics generation or emission of nonlinear fluorescence, each granting helpful information on the biological tissue, that can be exploited for diagnosis purposes. Adapting these nonlinear microscopy techniques to micro-endoscopy to access cluttered, small environment and in-vivo imaging is very promising while being a real challenge. It requires the miniaturization of the optics and the scanning mechanism into a compact and flexible probe [1]. In this workshop we will present endoscopy in general and our flexible and compact probe with its characteristics. Hence, we will show and talk about multimodal imaging, such as 2-photon, 3-photon, SHG, THG and CARS imaging, and some example usages including ex and in-vivo. Then we will perform 2-photon and SHG live-imaging and hands-on practice with the participants. [1] D. Septier, V. Mytskaniuk, R. Habert, D. Labat, K. Baudelle, A. Cassez, G. Brévalle-Wasilewski, M. Conforti, G. Bouwmans, H. Rigneault, and A. Kudlinski, “Label-free highly multimodal nonlinear endoscope,” Optics Express 30, 25020-25033 (2022).