Primary Hypothesis: All-cause mortality will differ by 25% between Endovascular repair (EVR) and Open repair. Secondary Hypotheses: Procedure failure, short term (12-month) major morbidity, number of hospital days, health-related quality of life and other procedure-related abnormalities will differ between the two AAA repair strategies. Primary Outcomes: All-cause mortality. Interventions: Patients will be randomized to one of these repair strategies for the elective treatment of AAA: (a) Open repair or (b) Endovascular repair (using FDA-approved devices). Study Abstract: Aortic aneurysm is the tenth leading cause of death in older men; AAA accounts for the majority of these deaths (about 10,000 deaths per year in the United States). Since one in 22 Veterans over the age of 50 have AAA and one in 200 have AAA with diameter greater or equal to 5.0 cm (making them candidates for elective repair), AAA is a major disease in the VA population. Questions about the relative safety and effectiveness of FDA approved EVR devices have been raised and remain unanswered. To answer these questions, this multi-center, randomized clinical trial comparing EVR with standard open surgery is proposed. Patients for whom elective repair of AAA is indicated and who are suitable candidates for both open repair and EVR will be eligible for the study. The anticipated duration of the study is 9 years with a proposed sample size of 900 patients. The first planning meeting took place on March 9-10, 2000 and the second planning meeting took place on November 6-7, 2000. The OVER protocol was submitted and reviewed by CSEC on May 10, 2001 and approved. The kickoff was June 12, 2002. The first DSMB meeting took place January 6, 2003. First annual meeting was held September 30, 2003; second DSMB meeting took place September 29, 2003. Third DSMB meeting held on April 19, 2004; second annual meeting was held on June 29, 2004. Fourth DSMB meeting was held on December 6, 2004; third annual meeting was held on March 15, 2005. The fifth DSMB meeting was held on July 19, 2005 and the fourth annual meeting was held March 21, 2006. The sixth DSMB meeting was held September 12, 2005. The seventh DSMB meeting was held on March 6, 2006. The eighth DSMB meeting was held on November 6, 2006. At its November 6, 2006 meeting, the DSMB discussed and approved unblinding of the study chair to prepare the short-term follow-up paper as specified in the study protocol. Initially the protocol called for this analysis to include one-year follow-up data. After discussions with the Trial Leadership, the DSMB approved use of two year follow-up data (reflected in DSMB minutes finalized February 20, 2007). This recommendation was subsequently approved by CSP in March 2007. The short-term outcomes manuscript was published in JAMA on October 14, 2009. The ninth DSMB meeting was held on May 14, 2007 and the fifth annual meeting was held on June 6, 2007. The tenth DSMB meeting was held on April 7, 2008. The eleventh DMC (name change only from DSMB to DMC) was held on June 22, 2009. The twelfth DMC meeting was held on May 24, 2010. A Site Investigator meeting was held in Boston, MA on June 9, 2010. The thirteenth DMC meeting was held on June 3, 2011 and a study close-out meeting was held on June 15, 2011 in Chicago, IL. The study's patient follow-up phase ended October 15, 2011.