Judges include "That '70s Show" television star Christina Moore, celebrity veterinarian Karen "Doc" Halligan and Vertical Horizon lead singer Matt Scannell. They will join fair board member Brian Sobel.
Actor and comic Jon Reep will emcee the barking pageant.
"It's really become a star-studded event," contest organizer Vicki DeArmon said. "It's crazy how excited everyone is to participate."
The ugly elite includes more than 25 pooches with names like Gizmo, Handsome Hector, Monkey Man, Rocco, Egar and Icky.
The uncomely competition is produced by the Sonoma-Marin Fair, which takes place June 23 through 27 at the Petaluma Fairgrounds, and is sponsored by doggie designers House of Dog.
More information is available at www.worldsugliestdogcontest.org.