Among the more recent biological tools being proposed and studied for dairy and swine management programs is somatotropin (growth hormone or GH). Advocates claim that somatotropin improves efficiency and thus decreases the cost of production in dairy cows and growing swine. With Food and Drug Administration (F&DA) approval of bovine somatotropin (SST) expected within the year in the United States and approval of porcine somatotropin (PST) being sought, food animal veterinarians need to be knowledgeable of somatotropin and must be prepared to advise clients on the use of the product as a management tool.