We attempted to correlate the in vitro and in vivo antitumor activities of cis-diammineglycolatoplatinum (254-S), a novel platinum complex, and cis-diamminedichloro-platinum (CDDP) against the established culture cell lines and xenografts of human non-small cell lung cancer (NSCLC) with their clinical effects, based on the previous finding that the cytotoxicity of CDDP depends on the area under the curve (AUC). The concentration of 254-S and CDDP inhibiting the in vitro growth of 4 cultured NSCLC lines by 50% (IC50) was 0.82-7.8 and 0.53-4.2 micrograms/ml, respectively, showing a similar level. Of the 4 cell lines, only the most sensitive line, RERF-LC-AI, showed an IC50 close to a specific concentration (0.50 for 254-S and 0.32 micrograms/ml for CDDP) that reproduces in vitro the clinical AUCfree (24.8 and 5.34 micrograms-hr/ml) of the respective drugs. We treated 6 lines of human NSCLC xenografts implanted in nude mice with 254-S and CDDP at a particular dose (13.2 and 3.7 mg/kg) that is equivalent to the clinical doses with respect to the plasma AUCfree. 254-S and CDDP exhibited significant antitumor effects on 2 and 1 of the 6 lines, respectively. These in vitro and in vivo findings were considered to be relatively well correlated with the reported clinical response rates of 15-19% for 254-S and 14-15% for CDDP.