State Route 399 is an 18.18-mile (29.26 km) road that connects Eagle Picher Mine to Lovelock, the nearest town.

SR 399's west terminus is at Eagle Picher Mine, which mines diatomite. SR 399 continues northwest and intersects Seven Troughs Road. SR 399 goes southwest on Seven Troughs Road until it meets SR 854, where it becomes Pitt Road. Pitt Road continues east until it meets North Meridian Road/SR 398 north of Lovelock.