I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty of whom or which I have heretofore been a subject or citizen; that I will support and defend the Constitution and laws of the United States of America against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I will bear arms on behalf of the United States when required by law; that I will perform noncombatant service in the Armed Forces of the United States when required by the law; that I will perform work of national importance under civilian direction when required by the law; and that I take this obligation freely without any mental reservation or purpose of evasion; so help me God. In acknowledgement whereof I have hereunto affixed my signature.
 

In some cases, INS allows the oath to be taken without the clauses:

that I will bear arms on behalf of the United States when required by law; that I will perform non-combatant service in the Armed Forces of the United States when required by law.

More information on the Oath of Allegiance can be found in the Code of Federal Regulations, Title 8 (Aliens and Nationality), Chapter I, Part 337 (8CFR337).