Italy handles all immigration and custom issues for San Marino, therefore all normal documentation requirements for entry into Italy apply for San Marino. Italy is party to the Schengen agreement, and as such, US citizens are allowed to enter San Marino for stays of up to 90 days for tourist or business purposes without a visa.
US citizens should ensure that their passports have at least 3 months remaining validity beyond the date of departure from San Marino.
Those traveling to San Marino for purposes other than the above-mentioned should first apply for a visa from an Italian Embassy or Consulate before leaving the United States.
For more information concerning visa requirements for San Marino, US citizens are advised to contact:
Embassy of Italy
3000 Whitehaven Street NW
Telephone: (202) 612-4221 / 4423 (accepting phone calls between 2pm to 4pm)
Fax: (202) 462-9406