Incumbent Republican Minority Leader Charlie Copeland has represented the 4th district since 2003. Copeland retired to run for Lieutenant Governor. Democrat Michael Katz won the open seat.
Democratic primary
Delaware Senate 4th district Democratic primary election, 2008
Incumbent Republican Steven Amick has represented the 10th district since 1995. Amick didn't seek re-election and Democrat Bethany Hall-Long won the open seat.
Republican primary
Delaware Senate 10th district Republican primary election, 2008
Incumbent Republican John Still III has represented the 17th district since 1988. Still didn't seek re-election and Democrat Brian Bushweller won the open seat.
Delaware Senate 17th district general election, 2008