We performed bioequivalent assessments of the generic (Paclitaxel Injection "SAWAI") and branded (Taxol Injection) formulations of paclitaxel injection on pharmacokinetics in dogs and in vitro/vivo antitumor activities. In the pharmacokinetics study in dogs, the 90% confidence intervals (CIs) for the differences in logarithm of C(max) and AUC(0-48) were log (1.01) to log (1.17) and log (1.01) to log (1.08), respectively. These were within the bioequivalent criteria of log (0.80) to log (1.25). In the in vitro study, both products showed concentration-dependent inhibition of the growth of 5 cultured human cancer cell lines, MCF7 (breast adenocarcinoma), A2780 (ovarian carcinoma), A549 (lung carcinoma), MKN45 (gastric adenocarcinoma) and MKN74 (gastric adenocarcinoma). The 90% CIs for the differences in logarithm of half maximal inhibitory concentration (IC(50)) were log (0.876) to log (1.110), log (0.856) to log (1.097), log (0.977) to log (1.167), log (0.879) to log (1.093) and log (0.936) to log (1.081), respectively. These were within the bioequivalent criteria. In the in vivo study, both products showed concentration-dependent inhibition of the growth of 3 human cancer cells, A2780 (ovarian carcinoma), A549 (lung carcinoma) and MDA-MB-231 (breast adenocarcinoma), xenografted in nude mice. And there are no significant differences between Paclitaxel Injection "SAWAI" and Taxol Injection. These results showed that Paclitaxel Injection "SAWAI" is bioequivalent to Taxol Injection.