Background: Acoustic cavitation which occurs at high intensities of ultrasound waves can be fatal for tumor cells; however, it can be used to destroy cancer cells as an efficient therapeutic method. On the other hand, it is known that the existence of nanoparticles in a liquid decreases the acoustic cavitation onset threshold. Materials and Methods: In this work, the combined effects of therapeutic ultrasound and gold nanoparticles (GNPs) on a breast carcinoma tumour model in BALB/c mice were studied. The tumour-bearing mice were divided into 4 groups (1) Control, (2) GNPs, (3) Ultrasound alone and (4) Ultrasound in the presence of GNPs. In groups 2 and 4, GNPs were injected into tumours. Therapeutic effects on tumours were evaluated by measuring relative tumour volume (RTV), doubling time (T₂) and 5-folding time (T₅) for tumours volume. Results: The T₅ showed a significant difference between ultrasound in the presence of GNPs group and the other groups. The maximum T₂ and T₅ were found in the ultrasound in the presence of GNPs group. Conclusion: Combined effects of ultrasound and GNPs can be used as a method for increasing the therapeutic efficiency on tumor cells.