Endoluminal microscopy and spectroscopy could significantly improve the efficiency of clinical endoscopic examination by allowing in-situ detection, staging and grading of potentially cancerous lesions. Indeed, high-end optical microscopy techniques such as confocal, coherence-gated and single-/multi-photon microscopy today deliver optical histology information and spectrally/spatially resolved measurements of tissue reflectance allow grading and staging of precancerous/cancerous lesions. Owing to the brisk development of MEMS technologies, miniaturization requirements satisfying the dimension requirements for endoscope integration have been met within the last decade and the present paper will report on the current and future development of MEMS-based endoscopes for optical diagnosis.