Guillen drove in 25 runs, scored 17, batted .345 and had seven homers and nine doubles in June, when he was named Royals Player of the Month. On June 7 at New York, he had seven RBIs on two home runs, including a grand slam, and a single.
The other nominees are Jason Giambi (Yankees), Dan Haren (Diamondbacks), John Lackey (Angels), Aramis Ramirez (Cubs), and Marcus Thames (Tigers).
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.