A team source confirmed on Sunday that Iguchi and Tomko were told of their release after San Diego defeated the Colorado Rockies, 2-1, at PETCO Park.
Iguchi, who signed a one-year deal worth $3.75 million in the offseason, was hitting .231 with two home runs and 24 RBIs in 81 games. He missed 47 games earlier in the season with a separated right shoulder.
Iguchi was hitting .125 in 64 at-bats since returning from the disabled list.
Tomko, who was signed to a Major League contract June 27 after being released by Kansas City, had a 1.93 ERA in six games.
Two players who do are pitcher Wade LeBlanc and second baseman Matt Antonelli, who figure to join the team in Los Angeles on Monday when the roster expands to 40 players.
The San Diego Union-Tribune was reporting Sunday that both players will be recalled Monday.
Antonelli, who hit .215 for Triple-A Portland this season, wasn't in the Beavers' lineup on Sunday against Tacoma.
LeBlanc, considered one of the Padres' top Minor League pitching prospects, was 11-9 with a 5.32 ERA with Portland, though he was 4-2 with a 2.86 ERA after the All-Star break.
LeBlanc could be in line to start Wednesday against the Dodgers, though the Padres might use veteran left-hander Shawn Estes in that spot.
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.