Objective: We aimed to assess the relationship between C-reactive protein (CRP) and the severity and diffusion of coronary artery lesions in patients with unstable angina pectoris (UAP) and the independent association of CRP with this clinical situation. Methods: This cross-sectional, observational study included 50 patients. Classification by Braunwald was used for UAP. The severity and diffusion of angiographic coronary disease were graded according to Reardon’s modified scoring system. Plasma CRP levels were quantified by immunoturbidimetry. Nonparametric tests were used for comparison of CRP and other risk factors, and logistic regression analysis for evaluation of independent association between CRP and unstable angina pectoris. Results: The severity score was 46±18 points in class IIB1 UAP, 36±20 points in class IIB2 and 53±18 points in class IIIB2 (p=0.017, class IIIB2 vs IIB2). Respectively, CRP levels were 6.6 mg/L, 3.8 mg/L and 4.8 mg/L (p=0.371, class IIB1 vs IIB2 vs IIIB2). Lesions with diffusion score 4 revealed higher CRP values than lesions with diffusion score 1 (11.1 mg/L vs 3.1 mg/L, p=0.048). Adjusting age, sex and smoking, assessment of partial correlation analysis showed a positive, moderately powerful and significant association between CRP levels and the severity and diffusion scores of the coronary lesions (r=0.30; p=0.034 and r=0.31; p=0.030, respectively) in the whole study group. Multiple logistic regression analysis showed no appreciable independent association between CRP and UAP (OR: 1.63, 95%CI: 0.90-5.63, p=0.093). Conclusion: Although, CRP was correlated with the severity and diffusion of angiographic coronary disease in patients with UAP, there was no independent association between CRP and clinical severity of UAP.