basic investigation for classification of anticancer drugs by pharmacological effects the most effective drugs based on the type of cancer are chosen for chemotherapy tumor cells can be targeted at the dna rna or protein level and most of the classical anticancer drugs interact with tumor dna in a timedependent manner or a concentrationdependent manner however it has been unclear to date whether a combination therapy is carried out by using exact classification thus it is necessary to reclassify a great number of anticancer drugs we propose a new classification system based on pharmacological effects of anticancer drugs classification of four anticancer drugs cisplatin carboplatin paclitaxel and gemcitabine was performed by the 345dimethyl2thiazolyl25diphenyl2htetrazolium bromide mtt assay the four anticancer drugs were grouped by ic50 values inhibitory concentration 50 in a timedependent manner and a concentrationdependent manner the present approach may be combined to enhance the chemosensitivity improve the dose of cytotoxic drugs and evaluate the effects of novel anticancer drugs