Obstacle and terrain warning radar system (1) for a rotorcraft (2), the system having at least two assemblies (10), each having at least one radar unit, said rotorcraft (2) including at least one main rotor (20) having at least two blades (22) and a rotor head (23). Each radar unit transmits a centrifugal radar beam (17) with angular beam width in azimuth α of at least 5° and beam width in elevation ε of at least 5°. Said assemblies (10) of at least one radar unit are positioned directly on said rotor head (23) between said blades (22), said radar system (1) electronically scanning the surroundings with angular coverage in elevation of at least +/−15° and mechanically scanning the surroundings with angular coverage in azimuth of 360°, and then informing the pilot of said rotorcraft (2).