Our offices are located at the US Embassy in Guatemala:

U.S. Commercial Service

Embassy of the United States of America
Avenida Reforma 7-01, Zona 10
01010 Guatemala

Ph.:   (502) 2326-4000
Ext.:  4259, 4261, 4227
Fax:   (502) 2331-7373
E-mail: guatemala.office.box@N0SPAM.mail.doc.gov

If you are sending mail from the USA:
U.S. Embassy
Unit 3306
APO AA 34024