One determinant of the survival time of cancer-bearing patients may be genetic factors. In chemically induced bladder cancers of mice, differences in survival time have been observed among several inbred strains. Genetic analyses of such differences in crosses between C57BL / 6 and NON mice revealed that the survival period is determined by two quantitative trait loci on mouse chromosomes 6 and 2, respectively. We explored the possibility that genetic alterations may be observed in the syntenic conserved chromosomal regions of human transitional cell carcinoma corresponding to mouse chromosomes 6 and 2. Human chromosome 7, containing a region syntenic to mouse chromosome 6, is reported to harbor frequent genetic alterations in bladder cancers. In this study, we investigated 70 human urothelial cancers for possible genetic alterations on human chromosome 20p and 20q containing regions syntenic to mouse chromosome 2. Allelic imbalances were observed in 22 cases (31.4%) on 20p and 18 cases (25.7%) on 20q. Those allelic imbalances, however, did not show a direct correlation with the prognosis of the patients. Higher grade tumors tended to show more frequent imbalances on chromosome 20; however, this tendency was not significant.