In this work, a novel self-healing system based on the use of polybenzoxazine precursor (PBP) as a healing additive is presented. PBP (M-n = 2300 g/mol, M-w/M-n = 2.6) is facilely synthesized in a reasonable yield by Mannich type polycondensation of bisphenol A, 1,6-diaminohexane with paraformaldehyde. The additive PBP faintly undergoes a thermal ring-opening reaction when contained in polysulfone (PSU) films. Thermal treatment at 160 degrees C enables PBP to chemically bind to PSU chains and form networks through the Friedel Crafts reaction, demonstrating a novel self-healing behavior. The extent of the recovery was studied using a stress elongation (%) test and found to be 55%. Thermal properties of the polybenzoxazine precursor and the healed sample were investigated.