Introduction: The absolute and proportional numbers of elderly patients diagnosed with localized prostate cancer (PCa) are on the rise. We examined treatment trends and reimbursement figures in localized PCa patients aged ≥80 years. Methods: Between 2000 and 2008, we identified 30 217 localized PCa patients aged ≥80 years in Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database. Alternative treatment modalities consisted of conservative management (CM), radiation therapy (RT), radical prostatectomy (RP), and primary androgen-deprivation therapy (PADT). For all four modalities, utilization and reimbursements were examined. Results: PADT was the most frequently used treatment modality between 2000 and 2005. CM became the dominant treatment modality from 2006‒2008. RP rates were marginal. RT ranked third, and its annual rate increased from 20.77% in 2000 to 29.13% in 2008. Median individual reimbursement of RT was highest and ranged from $29 343 in 2000 to $31 090 in 2008, followed by RP (from $20 560 in 2000 to $19 580 in 2008), PADT (from $18 901 in 2000 to $8000 in 2008), and CM (from $1824 in 2000 to $1938 in 2008). RT contributed to most of the cumulative annual reimbursements from 2003 (49.24%) to 2008 (72.97%). PADT ranked first from 2000 (54.56%) to 2002 (50.49%), but decreased by 19.40% in 2008. CM’s contribution increased from 4.42% in 2000 to 6.96% in 2008. RP’s share of reimbursements was stable during the study period. Conclusions: Our results, focusing on localized PCa treatment in patients aged ≥80 years, showed an important increase in rates, median cost, and proportion of cumulative cost related to RT. © 2018 Canadian Urological Association.