Clinical guidelines for the diagnosis of pigmented lesions of the skin are not always reliable. Surface microscopy (SM) represents an interesting approach to this problem. For this in vivo investigation, a stereomicroscope, a glass slide, and immersion oil are used. In the present study, the various criteria of SM that cannot be discerned by the naked eye are correlated with the histopathological structures in step-sectioned specimens. Characteristic SM features such as the pigment network, "black dots," or "irregular extensions" were found to correspond to particular histological findings. SM opens a new dimension of clinical morphology for the diagnosis and differential diagnosis of malignant melanomas, dysplastic nevi, or nonmelanocytic pigmented neoplasms, and facilitates a more reliable preoperative assessment of these lesions.