Ecthyma gangrenosum is a well recognized cutaneous manifestation of Pseudomonas aeruginosa infections in immunocompromised patients. Most cases of ecthyma gangrenosum have been associated with concomitant septicaemia. However, ecthyma gangrenosum rarely develops due to Ps. aeruginosa in the absence of bacteraemia. We report a rare case of a nonsepticaemic form of ecthyma gangrenosum presenting as a large solitary necrotic ulcer in a patient with acute myelogenous leukaemia. A culture from the lesion revealed the presence of Ps. aeruginosa, but the results of repeated blood cultures were negative. Histological examination revealed numerous tiny eosinophilic bacilli in the dermis and panniculus with Gram's stain.