A human ovarian carcinoma, IGROV-1, was xenografted into different sites (i.p., s.c., i.v., and intrasplenically) in nude athymic female mice to investigate the pattern of antitumour efficacy of FAA and compare it to that of doxorubicin and cisplatin, two established cytotoxic drugs. Ascitic and lung-growing tumours totally failed to respond to FAA, whereas s.c. and liver-growing tumours were significantly growth inhibited. This pattern of activity differs from that achieved by the two conventional cytotoxic drugs, which were active against the IGROV-1 tumour growing in all of the tested sites. These studies indicate that cytotoxicity is not the major determinant of FAA antitumour efficacy even against human tumour xenografts. Moreover, the dramatic difference between the sensitivity of lung and liver tumour colonies demonstrates the great importance of the site of tumour growth for FAA efficacy.