Thiazides and thiazide-type diuretics are recommended as first-line agents for the treatment of hypertension, but contemporary information on their use in clinical practice is lacking. We examined patterns and correlates of thiazide prescription in a cross-sectional analysis of baseline data from participants enrolled in the Systolic Blood Pressure Intervention Trial (SPRINT). We examined baseline prescription of thiazides in 7582 participants receiving at least 1 antihypertensive medication by subgroup, and used log-binomial regression to calculate adjusted prevalence ratios for thiazide prescription (versus no thiazide). Forty-three percent of all participants were prescribed a thiazide at baseline, but among participants prescribed a single agent, the proportion was only 16%. The prevalence of thiazide prescription differed significantly by demographic factors, with younger participants, women, and blacks all having higher adjusted prevalence of thiazide prescription than other corresponding subgroups. Participants in the lowest category of kidney function (estimated glomerular filtration rate <30 mL/min per 1.73 m2) were half as likely to be prescribed a thiazide as participants with preserved kidney function. In conclusion, among persons with hypertension and heightened cardiovascular risk, we found that thiazide prescription varied significantly by demographics and kidney disease status, despite limited evidence about relative differences in effectiveness.