The Americas Zone was one of three zones of competition in the 1978 Davis Cup. As in previous years, entries from South America were to be placed in one half of the draw, while entries from North and Central America, along with South Africa, were to be placed in the other. However, Canada, Mexico, Venezuela, and the Caribbean/West Indies withdrew a week before the draw, in protest over South Africa's participation. * The United States advanced to the Interzonal Zone.