Perhaps no factor can influence the cost of gain and animal performance more than the presence of subclinical swine diseases. Evaluating the health status of a herd or a group of purchased pigs will require the expertise of a veterinarian. Subsequent herd-health care and its supervision by a veterinarian specializing in swine can be an invaluable service. Subclinical health conditions ultimately will influence the pig's nutrient requirements, feed intake, and cost of gain. A successful preventative herd-health program in coordination with a veterinarian can be an important investment for the swine producer.