The ultrasonically-induced in vitro cell damaging effect of fluorine-containing anthracycline derivative (FAD104) was investigated. Sarcoma 180 cells suspended in air-saturated PBS were exposed to ultrasound for up to 60 s in the presence and absence of FAD104. The rate of inducing cell damage with ultrasound was doubled with 80 microM FAD104, while no cell damage was observed with FAD104 alone. This enhancement was significantly inhibited by histidine, which may suggest a sonochemical mechanism.