Fundamental and clinical evaluations of ten anticancer drugs were performed. The required qualities of an anticancer drug ideal for bladder instillation therapy are thought to be as follows: (l) a high sensitivity for bladder tumor cells; (2) a pKa which provides a high percentage of nonionized molecules in a pH 6–7 solution; (3) a log P in the range from −0.4 to −1.2 or from −7.5 to −8.0; and (4) a molecular weight over 200.