The concentration of copper, zinc and iron in the skin of patients suffering from lepra reaction was measured by diagnostic X-ray spectrometry (DXS) at the sites of the lesions before and after treatment with thalidomide. The results were compared with the levels of these elements in the skin of healthy individuals. No significant changes in the copper level of leprous skin were found. The zinc levels showed significant elevations in some lesions with no apparent trend. The iron level in the affected areas had highly elevated values in all cases of lepra reaction. However, in contrast to the fast clinical improvement which followed the treatment with thalidomide, the iron levels did not decrease for prolonged periods.