Pyoderma gangrenosum was first described in 1930 by Brunsting, Goeckermann and O'Leary. Nevertheless we found some illustrations in an atlas on dermatology, published by Marie-Nicolas Devergie in the first half of the 19th century, which appear to be pyoderma gangrenosum. In addition to discussions of typical syphilitic affections of the skin, Devergie's "Clinique de la Maladie Syphilitique" includes illustrations of gangrenous ulcers, which appeared unexpectedly after local and systemic therapy with mercury. Devergie interpreted those enlarging ulcers as a side effect of mercury therapy. Thus we were able to find evidence of pyoderma gangrenosum more than 100 years before first description in 1930. The etiology of this clinical picture is still unsettled. The favorite postulate has been a bacterial genesis which was the subject of numerous publications until the 1960s.