The dyeing of modified acrylic fabrics using indicaxanthin as a natural dye isolated from fruits of Opuntia ficus-indica has been studied in both conventional and ultrasonic techniques. Factors affecting the dyeing properties such as pH values, salt concentration, temperature, duration of dyeing bath, and ultrasonic power were studied. The optimal conditions for dyeing with indicaxanthin dye were carried out at 80 °C for 30 min at pH 3. Sonicator dyeing showed marked improvement in dye uptake. The results of fastness properties of the dyed fabrics were fair to good. Dyeing kinetics using conventional and ultrasonic conditions was compared. Color strength values obtained were found to be higher with ultrasonic than with conventional heating. Dyeing kinetics of modified acrylic fiber with indicaxanthin dye using conventional and ultrasonic conditions were compared. The values of dyeing rate constant, half-time of dyeing and standard affinity and ultrasonic efficiency have been calculated and discussed.