Aguilera pitched well for the Cubs in 1999, posting a 6–3 record with 8 saves and a 3.69 ERA in 44 games as a middle reliever, set-up man, and occasional closer. At age 38, he entered the 2000 season, his 16th season in the big leagues, as the team's closer. Aguilera went 1–2 with 29 saves in 54 appearances, but blew eight of his save opportunities and finished with a 4.91 ERA for the last-place Cubs.
