Rear module for a motor vehicle

The module has a rear frame (24) made of thermoplastic material, and comprising fixation units cooperating with fixation units (12) of a body shell (10) and fixation units (28) of a rear opening (14) such as rear door. Side rails (20) having extensions (26) are disposed under the body shell. The extensions having U shape are made up of metallic material and are disposed under the frame.