Taiwan has one of the highest incidences of upper tract urothelial cancer (UTUC) worldwide, especially in women; however, no nationwide, long-term follow-up study has evaluated this. We investigated the incidence of UTUC in Taiwan using data from the national population-based Taiwan Cancer Registry database (1985-2019). We divided the birth cohort into nine 5-year age groups and calculated the age-specific incidence for these groups according to the corresponding birth years. The average annual percent change in the incidence of renal pelvis cancer from 1985 to 2019 showed sex-specific differences, with 3.5% and 5.3% increases in the incidences in men and women, respectively. The age-specific incidence rate for renal pelvis cancer among women showed a gradual increase in the group with older women as well as an increase over time in each age group. The results of a birth cohort analysis revealed that younger cohorts had higher incidence rates of renal pelvis cancer than older cohorts did. We demonstrated that the incidence of UTUC is unusually high among older Taiwanese women and that younger cohorts have a high risk of UTUC than older cohorts.