Combination therapy with 5% minoxidil plus 0.5% anthralin was used to treat 51 patients with severe treatment-resistant alopecia areata. History of a cosmetically inadequate response to one or both drugs used as a single agent was present in 50 of the 51 patients. Therapy was relatively well tolerated except by 1 patient who developed a severe irritant reaction and was dropped from the study. Mild to moderate irritant dermatitis was seen in all remaining patients. Cosmetic response was seen in 5 (11%) of 45 patients who completed the 6-month study. Cosmetic response was maintained in 4 (80%) of 5 patients who continued treatment for as long as 84 weeks. All responders had evidence of hair regrowth by week 12. The rapidity and extent of hair regrowth were greater with combination therapy than with either drug used as a single agent. Serum and 24-hour urinary minoxidil determinations showed enhanced systemic minoxidil absorption, which was probably secondary to the irritant dermatitis in some patients; however, no clinical evidence of a systemic minoxidil effect was found. These data suggest that combination therapy using drugs with probable different mechanisms of action may provide a synergistic effect in alopecia areata.