After acquiring star goaltender Dominik Hasek via free agency, the Senators decided to trade Lalime to the St. Louis Blues for a 4th round conditional pick in the 2005 NHL Draft on June 27, 2004. Lalime was set to be the Blues starter during the 2004-05 season, however the lockout wiped out the season, and Lalime did not play any hockey that year.

 

During the 2005-06 season, he earned his first win with the Blues on October 11 against the Chicago Blackhawks, making 32 saves in a 4-1 victory. However, this was a season to forget for Lalime, as he finished the year with a 4-18-8 record, 3.64 GAA and a .881 save percentage. He also spent a part of the season in the AHL, where he posted a record of 6-6-1, 2.86 GAA and .903 save percentage with the Peoria Rivermen. On April 2, Lalime played his final game as a Blue, as he was suffered a torn ACL that had him out for the remainder of the season.

 

On July 1, 2006, Patrick was signed by the Chicago Blackhawks to a one year $700,000 contract, likely to be the backup to Nikolai Khabibulin. He ended up being injured just before training camp with a herniated disk. In his debut (first game) as a Blackhawk on February 7, 2006, Lalime stopped 34 shots and shutout the Vancouver Canucks as Chicago won the game 3-0. He went 4-6-1 in 12 games during the regular season with a 3.07 GAA and a .896 save percentage. His play with the Blackhawks was good enough for the club to re-sign him to another 1 year contract, this one worth $950,000