Mycosis fungoides (MF) is a cutaneous T-cell lymphoma (CTCL) characterized by its typical progress in three stages: the patch-, the plaque- and the tumour-stage. The incidence of mycosis fungoides rises with age and the average age at presentation is about 50. Children and adolescents are rarely affected and there are only few reports in the literature. We report a 12- and a 15-year-old boy showing refractory skin lesions not typical for mycosis fungoides. The histo- and immunohistological investigations and the detection of clonal T-cell receptor gamma gene rearrangements confirmed the diagnosis of early onset mycosis fungoides in both cases.