Treatment with 5-ALA enhanced ultrasound-mediated inhibition of osteosarcoma cell proliferation and ultrasound-induced osteosarcoma cell apoptosis in vivo and in vitro, associated with reducing the ΔψM and BcL-2 expression and increasing the levels of ROS production, Bax, p53 and caspase 3 expression. The gene discussed is CASP3; the disease is osteosarcoma.