Necropsy was performed on a sea lion (Zalophus californianus wollebaeki), sacrificed in an advanced (pre-terminal) stage of disease, possibly representative of the Galapagos epizootic of 1970-71. Predominant features of the disease were non-umbilicated multiple suppurative cutaneous nodules, debilitation and loss of motor power. Histopathological studies of the skin lesions disclosed suppurative cellulitis, with leucocytic invasion extending, in some instances, to all layers of the epidermis. Pseudomonas aeruginosa was recovered from cultures of blood and pus.