Background: In this study, we aimed to evaluate the effects of niacin on high sensitivity C reactive protein (hs-CRP) and cholesterol levels in non-ST elevated acute coronary syndrome (NSTE-ACS) patients. Methods: In this prospective, open label study, 48 NSTE-ACS were randomized to niacin or control group. Patients continued their optimalmedical therapy in the control group. In the niacin group patients were assigned to receive extended-release niacin 500 mg/day. Patients were contacted 1month later to assess compliance and side effects. Blood samples for hs-CRP were obtained upon admittance to the coronary care unit, in the third day and in the first month of the treatment. Fasting blood samples for cholesterol levels were obtained before and 30 days after the treatment. The primary end point of the study was to evaluate changes in hs-CRP, cholesterol levels, short-term cardiovascular events, and the safety of niacin in NSTE-ACS. Results: Baseline demographic, clinical and laboratory characteristics were similar between the two groups. Logarithmic transformation of baseline and 3rd day hs-CRP levels were similar between the groups; but 1 month later, logarithmic transformation of hs-CRP level was significantly lower in the niacin group (0.43  0.39 to 0.83  0.91, p = 0.04). HDL-C level was significantly increased in the niacin group during follow-up. Drug related side effects were seen in 7 patients in the niacin group but no patients discontinued niacin. Conclusions: Our findings demonstrate that lower dose extended release niacin can be used safely and decreases hs-CRP and lipid parameters successfully in NSTE-ACS patients.