In this study, the optimal dose of Lipofectamine 3000 and Turbofect to transfect adherent cell lines such as CHO-K1 and HEK293 cells in comparison with non-adherent H9T-cells with pEGFP-N1 and pCDH was identified.Lipofectamine 3000 is a new transfection reagent which is claimed to be more efficient than other transfection reagents like Turbofect. Transfection efficiency could be affected by the nature of target cell line and vector.Transfection efficiency and cytotoxicity of each reagent was identified by using flow cytometry and XTT assay, respectively.Lipofectamine 3000 was more efficient in transfecting pCDH, while Turbofect was more efficient in separate transfection of CHO-K1 and HEK293 with pEGFP-N1. Lipofectamine 3000 could be cytotoxic in transfecting H9T-cells with pCDH. Also, H9T-cells were not sufficiently transfected with each plasmid vector by using each Lipofectamine 3000 and Turbofect. Turbofect had less cytotoxicity effect on all three cell lines than Lipofectamine 3000.Transfection of suspended cells like H9T-cells by using Lipofectamine 3000 and Turbofect would not result in sufficient transfection.Lipofectamine 3000 is the best choice for transfection of CHO-K1 and HEK293 with pCDH while Turbofect is preferably used in transfecting these cell lines with pEGFP-N1 (Tab. 1, Fig. 2, Ref. 26).