Treatment results in 65 patients with borrelial lymphocytoma (22 on the ear lobe and 43 on the breast), registered at the Department of Infectious Diseases, University Medical Centre Ljubljana, from January 1986 to March 1995, are presented. When lymphocytoma was the sole manifestation of Lyme borreliosis or associated with erythema migrans only patients were treated orally with doxycycline, phenoxymethylpenicillin or amoxicillin for 14 days, or azithromycin for 5 days (15, 19, six and 12 patients, respectively). When signs and symptoms of disseminated borrelial infection were present (seven patients) or clinically suspected (six patients) patients received ceftriaxone or penicillin G i.v. for 14 days. Lymphocytoma disappeared within a few weeks after the institution of treatment. The speed of regression depended on the duration of lymphocytoma before the institution of therapy. The number of patients was too low and pretreatment characteristics were too heterogeneous to enable a reliable comparison of the efficacy of different antibiotics. It appears that the effectiveness of doxycycline and azithromycin is comparable and that amoxicillin performs well, but some findings may indicate that phenoxymethylpenicillin is less effective than some newer antibiotics. The optimal agent, dosage and duration of therapy for borrelial lymphocytoma have not been determined.