Rhodamine 123 (Rh123) is a red fluorescence dye, which is accumulated more and retained longer in the mitochondria of malignant transformed cells. In this study, the suppressive effects on the growth of cultured urogenital carcinoma cells (PC-3 and LNCaP from prostate carcinoma, T-24 from bladder cancer, and SV-HUC-1 human ureteral transitional cell transformed by SV virus in vitro, ACHN, YCR-1 and RCF213 from renal cell carcinoma) were examined. The cell growth of PC-3, LNCaP, T-24 and SV-HUC-1 was suppressed significantly in a dose dependent manner, but that of cells derived from renal cell carcinoma was not suppressed. The uptake and elimination of Rh123 in PC-3, ACHN and YCR-1 were not significantly different. When administered with verapamil and buthionine sulfoximine, which are reported to be chemical modulators of anticancer agents, Rh123 suppressed the growth of ACHN and YCR-1 significantly. Rh123 seems to have an anticancer effect against the urogenital carcinomas, and the role of Rh123 with hyperthermia, photodynamic therapy and chemotherapy requires further investigation.