The rising incidence rates of mycosis fungoides (MF) call for an explanation. Thus, environmental and lifestyle factors were speculated to play a role in the development of lymphoproliferative diseases. It is thought that continuous activation of skin T helper lymphocytes leads to malignant transformation of a specific clone. Possible risk factors that have been implicated are occupational chemical exposure, radiation, drugs and infections. The carcinogenic process is probably multifactorial and multistep, combining the genetic predisposition of the individual and his immune status with various exogenous factors. Using advanced and accurate exposure assessment tools, recent epidemiological data indicate that occupational exposure to chemicals, primarily to aromatic halogenated hydrocarbons, is a major risk factor to develop MF in men (odds ratio 4.6), while exposure to pesticides, a subgroup of the aromatic halogenated hydrocarbons, is a risk factor in both genders (odds ratio 6.8 for men and 2.4 for women). Apparently, concomitant infection with Staphylococcus aureus or with Borrelia species and chronic exposure to UVR are minor risk factors for the development of MF. Further assessment of occupational and environmental exposures is essential for the evaluation of their contribution to the etiology of MF. This will allow the application of preventive and surveillance measures along with adjustment of existing health policies.