Renin-angiotensin-aldosterone system (RAAS) blockers are underutilized in patients with chronic kidney disease (CKD). We aimed to determine barriers against the use of RAAS blockers in these patients. Patients with stage 3-5 CKD referred to Hacettepe University Hospital Nephrology Unit during a 1 year period were evaluated for RAAS blocker use. Two hundred and seventy-nine patients (166 male, 113 female) were analyzed. The mean age of the patients was 56.7 +/- 15.2 years, mean serum creatinine was 2.45 +/- 1.44 mg/dL, and mean glomerular filtration rate was 33.3 +/- 15.1 mL/min. The mean follow-up time was 22.0 +/- 21.9 months and the clinical visit number was 4.0 +/- 3.5. Angiotensin-converting-enzyme inhibitors or angiotensin receptor blockers were used by 68.8% of all patients and 67.7% of diabetic patients at the time of analysis. In 82.1% of patients, RAAS blockers had either been used earlier or were being used. Hyperkalemia was the principal reason for both not starting and also discontinuing these drugs in patients with CKD. In 37.4% of patients, reasons for not starting RAAS blockers were unclear. This study showed that hyperkalemia is the major barrier against the use of RAAS blockers in patients with CKD. There was, however, a subset of patients who did not receive RAAS blockers even without clear contraindications.