A draft of guideline for phase III study of anticancer drugs was presented, and its objective problems in practical aspect was discussed. The anticipated of phase III study is to evaluate the clinical usefulness of anticancer drug in terms of effectiveness and toxicity. And the comparative study of new drugs with standard therapy is most important. The comparative study includes two trials: randomized controlled trial and the second non-randomized controlled trial. Considering the precision of study, the randomized controlled trial is most rational, but it includes some controversies in practical use and ethical aspect. On the other hand, non-randomized controlled trial includes some problems on comparability in relation to prognostic factors.