The crash occurred shortly before 1:30 p.m. when a 20-year-old Stockton man riding a motorcycle west on Highway 84 lost control west of state Highway 35 while trying to negotiate a left curve in the road, according to the California Highway Patrol.
The motorcycle crossed over into oncoming traffic, and collided head-on with an eastbound 2007 Lexus driven by a 67-year-old Menlo Park man, CHP officials said.
The motorcyclist suffered severe but non-life threatening injuries.
The collision closed Highway 84 in both directions for 40 minutes, and one-way traffic control remained in effect until both lanes reopened at 2:57 p.m.