Background: Regression in malignant melanoma has been studied from different perspectives, but its mechanisms as well as its prognostic significance are not well clarified. Methods: A total of 25 studies retrieved from a Medline search for the words "regression" and "melanoma" were reviewed. Results: While some authors found histological evidence of regression to be a bad prognostic sign, others stated that it had no meaning in regard to prognosis, but some used the evidence of metastasis as a criterion and others used the disease-free survival as indicator of a good versus a bad prognosis. Very few articles have focussed on the histopathologic features of regression. In most other studies, no mention is made how, precisely, the authors identified regression, and when criteria were given, they differed considerably. Articles that attempted to understand the mechanisms of regression in melanomas mainly focussed on the analysis of the cellular infiltrate assuming that regression is a sign of immunological destruction of the malignant neoplasm by the organism that bares it, but as of this date it is not known why regression occurs, why it is seen more commonly in thin melanomas, and whether it is consequent to spread of melanoma cells to a lymph node or unrelated to it. Conclusions: A larger study correlating regression with overall survival of patients with melanoma has to be undertaken. Only melanomas with unequivocal regression identified by reliable and repeatable criteria should be included. Similarly, research on pathophysiology of regression requires precise and repeatable criteria for recognition of regression before meaningful results can be expected.