The great majority of cutaneous melanocytic lesions can be readily classified as one of the defined diagnostic entities, either benign or malignant. Therefore, only in a minority of lesions, it is necessary to employ ancillary techniques to help in the diagnosis. The most popular and probably the most helpful of these is immunohistochemistry: an area in which Dr McNutt has made some of his most important scholarly contributions. Following Dr McNutt's lead, in this article, we describe the use of immunohistochemistry as a diagnostic aid in dermatopathology as well as the potential pitfalls commonly encountered in practice.