UNLV Safe Community Partnership chief Erin Breen says police will hand out tickets Tuesday to motorists who fail to stop for the green-clad pedestrians crossing streets.
Fines can run $190 and up.
Pedestrians can also be ticketed for trying their luck crossing streets outside a crosswalk.
Breen says pedestrian deaths in Clark County are up 50 percent so far this year.
The St. Patrick's Day enforcement comes after a costumed turkey tested drivers in November, and Santa trolled crosswalks around Christmas.