An Amazon River dolphin (Inia geoffrensis) developed a dermatologic syndrome characterized by the occurrence of slow-growing, nodular, s.c. abscesses. Initial biopsies, cultures, and cytologic analysis of needle aspirates from the abscesses indicated steatitis with probable secondary, gram-negative bacterial infection. Treatment with dietary vitamin E supplement and broad-spectrum antibiotics yielded minimal improvement. Subsequent cultures revealed Streptococcus iniae in addition to several gram-negative bacteria. Vigorous surgical management of the abscesses, including lancing, debridement, and irrigation, combined with antimicrobial therapy specific for Streptococcus and gram-negative organisms, and improvement of the animal's diet and environmental water quality led to gradual recovery. When the animal was ill, it demonstrated an inflammatory leukogram and transient uremia. Streptococcus iniae is a serious pathogen of aquacultured fishes and humans and should be included in the differential diagnosis of chronic dermatopathy in river dolphins. Specific antimicrobial therapy, excellent water quality, surgical management of abscesses, and adherence to sanitary protocols should be observed in cases of suspected S. iniae infection in dolphins.