Fish, mollusks, marine crustaceans and marine mammals were implicated as vehicles in approximately 11% of foodborne disease outbreaks reported in the United States during the years 1970–1978. Tuna, clams, oysters, shrimp, and crab frequently were vehicles. These animals can acquire the dinoflagellates responsible for ciguatera, paralytic shellfish poisoning and neurotoxic shellfish poisoning from their marine habitats. Many common marine organisms found in and on fish can decarboxylate histidine to histamine, and do so during improper storage of fish. Vibrio parahaemolyticus and Clostridium botulinum type E are of marine origin, and C. botulinum types A and B can wash from soil into aquatic environments. Pollution of estuaries by domestic sewage and subsequent ingestion of raw or improperly cooked shellfish harvested from the polluted waters have led to outbreaks of typhoid fever, hepatitis A and cholera. Staphylococcal intoxication, shigellosis, salmonellosis, and Clostridium perfringens gastroenteritis (as well as typhoid fever, hepatitis A and cholera) have been acquired because seafoods were mishandled during preparation. Preventive and control measures include safe disposal of sewage, monitoring of sanitation practices and food-handling practices, monitoring shellfish and their growing waters for pathogens and indicator organisms, and education and training.