The 2003 Western Illinois Leathernecks football team represented Western Illinois University as a member of the Gateway Football Conference during the 2003 NCAA Division I-AA football season.
They were led by fifth-year head coach Don Patterson and played their home games at Hanson Field.
The team received an at-large bid to the NCAA Division I-AA Football Championship playoffs, where they defeated Montana in the first round and lost to Colgate in the second round.
6 in The Sports Network's postseason ranking of Division I-AA.
This college football 2000s season article is a stub.