Bis[di-n-butyl (4-aminosalicylato)tin] oxide [NSC: 628561] (compound 1), bis [diphenyl(4-aminosalicylato)tin] oxide [NSC: 628562] (compound 2), and six other analogous compounds of the type [n-Bu2 (XYZ-C6H2COO)Sn]2O (compounds 3 to 8), were tested in vitro at the National Cancer Institute, Bethesda, Maryland, USA, for cytotoxic activity against a series of human cell lines. Compounds 1, 6 and 8 score globally satisfactorily since four of the five relevant sensitivity or selectivity parameters, DGI50, DTGI or DLC50, DH and MGDH, are statistically significant. Compounds 3 and 7 are less satisfactory because only three such parameters are statistically significant. For compound 2, only two of the parameters are significant.