The significance of Pseudomonas aeruginosa in cutaneous medicine has been largely ignored in the dermatologic literature. The pathogenic nature of this organism in a healthy person is limited, presenting usually as the "green nail" syndrome, otitis externa, or toeweb infection. Secondary infection of cutaneous lesions with epidermal destruction and characteristic purulence is pathognomonic of Pseudomonas and may be explained by the organism's elaboration of proteolytic and elastolytic enzymes. The toxins elaborated by Pseudomonas in extensive cutaneous infection may be lethal in the absence of septicemia. Ecthyma gangrenosum, pathognomonic of Pseudomonas septicemia, must be more readily recognized by the consulting dermatologist. The role of a Shwartzman phenomenon in Pseudomonas -complicated pyodermas is discussed. Cases of these conditions are reported. Topical and systemic therapy are discussed.