Five of 10 patients receiving long-term recombinant interferon alpha-2b therapy complained of considerable hair loss. The pull test and the trichogram showed a telogen count consistent with a telogen effluvium. In 2 patients the telogen count progressively improved despite continuing the treatment, whereas in 3 patients the trichogram continued to show an increased telogen count until interferon therapy was discontinued. Pohl-Pinkus hair constrictions were also present in 2 patients.