Abstract： A 46-year-old man presented with a two-year history of painful and vegetating ulcer and scarring of both legs, as well as a one-year history of folliculitis-like papules and erythema on the trunk. The histological examination of lesions on the legs revealed fibrinoid necrosis of the vascular wall and neutrophilic infiltration with nuclear dust and occasional multinucleated giant cells in the dermis, while that of lesions on the back demonstrated residual follicle epithelium at the edge of a small abscess, and perivascular infiltration with a moderate number of neutrophils, lymphocytes and nuclear dust in the superficial and deep dermis. Morganella morganii was isolated by bacterial culture from the tissue specimens from the lesions on the legs, but not from those on the trunk, and the isolate was sensitive to ceftazidime. The patient was diagnosed with vegetative pyoderma gangrenosum. The condition was controlled after treatment with low-dose prednisone,tripterygium glycosides, dapsone and ceftazidime.