Background/objectives: Chronic kidney disease (CKD) and cancer are both common in older patients; whether CKD increases risk for cancer is unclear. This study evaluated CKD as a risk factor for cancer mortality in a large cohort of hypertensive patients. Study design: We did post-hoc analyses of in-trial and post-trial data from participants in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). Setting and participants: Participants were ≥ 55 years old with hypertension and one other additional risk factor for coronary heart disease. Predictor: Baseline estimated glomerular filtration rate (eGFR). Outcomes: Cancer mortality was ascertained by cancer-related deaths reported in national databases during and after the trial. Cox proportional hazard models were used to calculate hazard ratios (HRs) adjusted for possible confounders and were stratified by baseline GFR. Results: Participants' mean age was 66.9 years. After a mean follow-up of 8.9 years, there were 2,338 reported cancer- related deaths. Participants with GFR < 45 mL/min/1.73 m2 were at increased risk of cancer mortality compared to those with GFR ≥ 90 mL/min/1.73 m2 (adjusted HR 1.54 (1.22-1.94), p-value for trend 0.004). These findings were consistent across subgroups defined by race, gender, and diabetes. Participants with GFR < 45 mL/min/1.73 m2 were at higher risk for mortality related to colon cancer (p-value for trend 0.048, HR 2.28 (1.12-4.62)) and urinary tract cancer (p-value for trend 0.001, adjusted HR 2.95 (1.14-7.65)). Limitations: This is a post hoc analysis of clinical trial data. Conclusions: In a large cohort of hypertensive patients, GFR < 45 mL/min/1.73 m2 was associated with a higher risk of cancer-related mortality.