Background: Mycosis fungoides (MF) is a chronic cutaneous T-cell lymphoma characterized by small cells with cerebriform nuclei that usually express a mature peripheral T-helper cell (CD4+) immunophenotype. Its evolution is typically quite slow, with years between the first manifestations and development of advanced stages of disease. Objective: The purpose of the present paper is to contribute to the material about MF already present in the literature. The review articles that have appeared to date fundamentally address the morphological characteristics, diagnostic criteria and treatment of the disease; in contrast, the present study centers on the evolution of the incidence of MF and on the knowledge of the possible risk factors implicated in its development. Methods: Review of published papers about MF epidemiology. Results: The evidence suggests that the incidence is increasing, but this may be artifactual due to improved diagnostic techniques. The risk of MF is limited to gender and race, being higher in males and in blacks. Survival is highly stage dependent, but 90% of patients survive 15 years with only 10% of cutaneous involvement. Few risk factors have been identified, but several studies have found an association with industrial exposure, particularly to oils. Conclusion: MF is a rare disease and its risk factors have not been studied in any great detail. A European case-control study in progress will substantially increase the evidence available and progress towards identifying a prevention strategy.