||The interaction of light with tissue can be used at both the macro and the micro levels for the detection of early cancers and pre-cancers. At the macro level, simple and multimodal reflectance and fluorescence imaging can be used successfully to detect and delimit early pre-cancerous lesions in the lung, cervix and oral cavities clinically. Further fluorescence imaging can so improve the determination of the surgical field in oral cancer surgery that it reduces recurrence rates and possibly mortality. Optical Coherence Tomography (OCT) imaging can be similarly utilized to visualize and quantify the structural changes associated with epithelial disease. At the micro level, in vivo (in vivo confocal and multiphoton microscopy) and ex vivo (quantitative absorption and fluorescence microscopy) can be used to detect/screen/manage pre invasive epithelial lesions of the oral cavity, cervix, lung and skin. Examples of the application of these technologies to human cancers and pre-cancers will be presented.