MISCHA Barton seems to be trying really hard to wiggle out of doing “The O.C.” any longer.

Barton, worried about the show’s spiraling ratings – and concerned about being typecast as a bratty teen – frequently calls in sick or arrives late to the set, according to a report in Life & Style magazine.

The publication quotes insiders who work on the show as being annoyed by Barton’s sickouts and tardiness – especially since she’s been known to hit the town and party hearty (and is the frequent subject of gossip-column items).

“She’s definitely flirting with leaving the show,” says one source. “But the real problem now is that she isn’t taking work seriously.”

Barton, 20, has played pampered princess Marissa Cooper on “The O.C.” since the Fox show’s 2003 premiere.

Once a hot ticket among the teen set, “The O.C.” has seen its ratings drop from nearly 10 million viewers its first season to around 5.4 million this season, according to Nielsen.

Barton co-stars on the show – which revolves around the privileged lives of people in Orange County, Calif. – with Peter Gallagher, Kelly Rowan, Benjamin McKenzie, Adam Brody and Rachel Bilson.

“We don’t comment on rumor or speculation,” said a spokeswoman for Warner Bros., which produces “The O.C.”

Barton has been romantically linked to Cisco Adler, “Brokeback Mountain” co-star Jake Gyllenhaal and Hollywood oil heir Brandon Davis.

She’ll be seen in the upcoming movies “Hexxx,” “Closing the Ring” and “Decameron: Angels & Virgins.”

michael.starr@nypost.com