List of United States senators in the 108th Congress

This is a complete list of members of the United States Senate during the 108th United States Congress listed by seniority, from January 3, 2003, to January 3, 2005. In this congress, Jeff Bingaman (D-New Mexico) was the most senior junior senator and Mark Dayton (D-Minnesota) was the most junior senior senator

Order of service is based on the commencement of the senator's first term. Behind this is former service as a senator (only giving the senator seniority within his or her new incoming class), service as vice president, a House member, a cabinet secretary, or a state governor. The final factor is the population of the senator's state.

Senators who were sworn in during the middle of the two-year congressional term (up until the last senator who was not sworn in early after winning the November 2004 election) are listed at the end of the list with no number.