Can I file for citizenship without having my green card?

USCIS states that you can still apply for naturalization even if you have lost your green card. Although the application for naturalization asks for a copy of the card, you can submit a letter of explanation and/or present a police report that shows you have lost your permanent resident card. In addition, you must submit a copy of any other entry document in place of the copy of the Permanent Resident Card. However, USCIS does recommend that you file for a replacement card, especially if you will not be applying for naturalization for another 6 months or if you cannot provide another entry document. CITATION: Page 79. http://www.uscis.gov/sites/default/files/USCIS/About%20Us/Electronic%20Reading%20Room/Customer%20Service%20Reference%20Guide/Permanent-Residents4-3.pdf