Argentina, Bolivia, Chile, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, Equatorial Guinea, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Spain, Uruguay, Venezuela...

more details pls see http://www.answers.com/Spanish%20Language

In the Caribbean: Puerto Rico, Cuba, Dominican Republic.
In Europe: Spain
In Central America: Honduras, Guatemala, Nicaragua, Mexico, El Salvador, Panama and Costa Rica.
In South America: Chile, Colombia, Argentina, Bolivia, Venezuela, Uruguay, Paraguay, Ecuador and Peru.

And of course there's lots of people in the United States that speak Spanish although it's not an official language.