The use of high resolution, in vivo confocal imaging may offer a clinical tool to detect early neoplasia and reduce the incidence and mortality of cancer. Our laboratory is currently examining the feasibility of using confocal microscopy for non-invasive diagnosis of dysplasia and early carcinoma in epithelial tissue. We are performing a series of ex vivo studies investigating the optical properties of normal and abnormal biopsies to quantify the diagnostic capability of this technology to discriminate between normal and pre-cancerous tissue. These studies use a near real time reflectance confocal microscope to acquire images at various depths throughout the epithelium. To date, we have completed a twenty-five patient study of cervical biopsies and have acquired images from six patients of an approved twenty-two patient study in the oral cavity. The cervical study has shown a distinct difference between normal and dysplastic tissue which can be used diagnostically, while initial results from the oral cavity are promising even with increased keratin scattering. In conclusion, our examination of normal and precancerous biopsies has demonstrated the confocal microscope's ability to image sub-cellular morphology at a resolution making accurate diagnosis possible and supporting this technique's potential for in vivo assessment of dysplasia.