Follicular mucinosis (alopecia mucinosa) is often associated with malignancies including mycosis fungoides and Sézary syndrome, but not adult T-cell leukemia-lymphoma (ATLL). We report a 49-year-old male patient who had pruritic follicular papules and erythemas clinically, and follicular and perifollicular infiltrates and follicular mucin deposition histopathologically. The patient showed 11% of flower-shaped atypical lymphocytes in blood examination and positive human T-cell leukemia virus type 1 antibody in serology, consistent with the chronic type of ATLL. This case seems to be a very rare association of follicular mucinosis and chronic ATLL, suggesting that malignant T cells may have a feature of folliculotropism as well as epidermotropism.