State Road 399 (NM 399) is a 3.185-mile-long (5.126 km) state highway in the US state of New Mexico.

NM 399's northern terminus is at U.S. Route 84 (US 84) and US 285 in Sombrillo, and the southern terminus is a continuation as County Route 120 (CR 120) at CR 127 in La Mesilla.