Lyme disease has been suspected to be one cause of secondary anetoderma. We present a 25-year-old male patient with multiple lesions of anetoderma with a diameter of up to 2 cm that developed within the last 4 weeks without subjective symptoms. The histopathologic pattern was similar to the inflammatory stage of acrodermatitis chronica atrophicans. Polymerase chain reaction analysis out of the paraffin-embedded tissue, confirmed by sequencing of the obtained nucleotide product, revealed a part of the 23 S ribosomal RNA gene of Borrelia burgdorferi sensu lato. Enzyme-linked immunosorbent assay showed an increased serum IgG titer against B burgdorferi corroborated by Western blot analysis. After a treatment with oral doxycycline (100 mg twice a day) for 30 days the anti-B burgdorferi titer decreased significantly and no new lesions appeared. Some cases of anetoderma might be caused by Borrelia and patients with anetoderma should be examined for borreliosis including serology and polymerase chain reaction of lesional skin. In cases of Borrelia-induced anetoderma, early antibiotic treatment could prevent further progression of the disfiguring skin lesions and the underlying disease. (J Am Acad Dermatol 2003;48:S86-8.)