Objective: Atherosclerosis is a chronic inflammatory disease. Statins suppress the inflammation in the plaque. This cross-sectional study was planned to evaluate the effect of statins on plaque T cell activation markers in patients with stable angina pectoris undergoing coronary intervention and atherectomy procedures. Methods: Twenty-six patients with stable angina with suitable for atherectomy coronary lesions were enrolled in the study. Fourteen of 26 patients who had been taking statin treatment for at least six months were assigned to the Group 1 (Statin group) and 12 patients who had not received any lipid lowering treatment comprised the Group 2 (Control group). Atherectomy specimens were studied with single and double immunohistochemical staining (CD25, CD69, and CD40L). Statistical analysis was performed using Student's t-test and Fisher's exact test. Results: There was no significant difference between the total tissue area of sections (Group 1: 8.4±0.9 mm2, Group 2: 7.8±0.9 mm2, p>0.05). CD3, CD25, CD69, and CD40L positive cells did not show statistically significant difference between the groups in unit area (mm2). There was no significant difference between the groups for percentage of T lymphocytes expressing CD25 (Group 1: 7.8±4.6%, Group 2: 7.8±5.9%, p=0.97) and CD 69 (Group 1: 12.9±4.6%, Group 2: 15.5±5.2%, p=0.203). The expression of CD40L was significantly lower in Group 1 than in Group 2 (Group 1: 4.8±3.9%, Group 2: 11.2±8.7%, p=0.034). Conclusion: We concluded that, statin treatment may decrease the expression of CD40L on plaque T lymphocytes in patients with stable angina pectoris.