We used a proteomic approach to compare the differentially regulated protein expression profiles of cisplatin-naïve and cisplatin-resistant bladder cancer cell lines to screen candidate molecules related to cisplatin resistance. The cisplatin-resistant cell line T24 was established by the stepwise exposure of T24 cells to up to 40 μM of cisplatin. We performed a comprehensive study of protein expression in bladder cancer cell lines that included cisplatin-naïve (T24) and cisplatin-resistant cells (T24CDDPR) by means of agarose two-dimensional gel electrophoresis followed by analysis of liquid chromatography tandem mass spectroscopy. We identified 25 obviously different spots for T24 and T24 CDDPR. Seven spots had increased expression and 18 spots had decreased expression in T24CDDPR compared to those in T24. Cytoskeletal proteins and enzyme modulators were prominent among differential proteins. Of the 25 proteins, we selected HNRNPA3, PCK2, PPL, PGK1, TKT, SERPINB2, GOT2, and EIF3A for further validation by Western blot. HNRNPA3, PGK1, TKT, and SERPINB2 had more than 1.5-times incremental expression in T24CDDPR compared to that in T24. PCK2 and PPL expressions were decreased less than 20% in T24CDDPR compared to that in T24. The results of 25 new proteins in this study could be valuable and could lead to the development of a new molecular marker.