This study aims to synthesize and characterize new disperse dyes based on modification of curcumin natural dye. When these dyes were used on polyester fabric, the resulting dyed fabrics had good colour strength. Without the use of a mordant or dispersion agent, they also demonstrated good light fastness and other fastness characteristics. Two steps were involved in the dyes' synthesis. The initial p-amino phenol was diazotized (0.01 mole, 1. 09 g) or 2-chloro-p-nitroaniline (0.01mol, 1.72 g) in hydrochloric acid with sodium nitrite. The Second step is coupling with curcumin (0.01mol, 3. 68 g) to give two disperse dyes D1 and D2 respectively. Dyeing polyester fabric take place in IR machine and also, Ultrasonic dyeing with dispersing agent and without dispersing are performed. Dyed polyester fabrics without dispersing agent gave higher exhaustion and fixation values than polyester dyed with dispersing agent. Also, they showed higher fastness properties against washing, rubbing, perspiration and light fastness. Modified curcumin dyes also, impart dark yellow colour without using mordant. In this work, analytical and spectral data were used to confirm the structures of the new disperse dyes that were created by modifying the naturally occurring color curcumin.