We report the DNA content in simultaneous renal and papillary transitional cell carcinomas in the same kidney with a subsequent metastasis of the transitional cell carcinoma to a left supraclavicular lymph node. The flow cytometric DNA analysis revealed aneuploid stemlines with identical DNA indices in both the transitional cell carcinoma and the metastatic lesion and a diploid pattern in the renal cell carcinoma. A discussion of these findings and the potential implication of DNA ploidy analysis in similar situations is presented.