Forty-five patients with cutaneous T-cell lymphomas (CTCL), 32 with mycosis fungoides (MF) and 13 with Sézary syndrome (SS), were treated with interferon-alpha 2a (IFN-alpha 2a) (6-9 x 10(6) IU daily) for 3 months. Those responding to treatment were then treated with interferon-alpha alone (6-9 x 10(6) IU three times weekly), and non-responders received a combination of etretinate (0.5 mg/kg/day) and IFN-alpha 2a in similar concentrations. After 12 months of treatment, 28/45 patients (62.2%) were in complete or partial (greater than 50%) remission. Of these, 17 (60.7%) were receiving IFN-alpha alone and 11 the combined interferon-retinoid therapy. Of the patients with MF stage I and II, 20/25 were responders (12 receiving IFN-alpha alone and eight on combined therapy), whereas only 8/20 with stage IV or SS responded to treatment (five receiving IFN-alpha 2a alone and three combined therapy). These results suggest that the association of etretinate with low-dose recombinant IFN-alpha 2a is an effective means of treating epidermotropic CTCL, particularly in the early stages.