Background: High sensitive C-reactive protein (hs-CRP) has been shown to be associated with asthma in recent studies. However, the relationship between hs-CRP and the control of asthma has not been clearly identified yet. Objective: To investigate the association of hs-CRP with asthma control test (ACT), which reveals the degree of asthma control, and to compare hs-CRP in adults with mild and moderate asthma in chronic, stable asthmatic patients. Methods: Thirty patients with physician-diagnosed asthma (11 mild, 19 moderate), and 30 healthy patients were enrolled in the study. In addition to medical history and physical examination, asthma was assessed according to GINA guideline. Respiratory function tests (RFT) and ACT were performed. The serum hs-CRP levels of all cases patients were measured. Results: The levels of hs-CRP in asthmatic patients were significantly higher than those in the control cases (p=0.002). The serum hs-CRP levels in the moderate asthmatics were significantly higher than those in the mild asthmatic ones (p=0.04). When asthmatic cases were divided into two groups according to ACTs; the levels of hs-CRP in the groups of ACT ≤ 20 (uncontrolled groups) were significantly higher than the groups of ACT ≥ 20 (controlled groups) (p=0.02). The hs-CRP levels showed significant correlations with ACT (p=0.00, r=-0.91) and asthma severity (p=0.04, r=038) in asthmatic patients. Conclusion: In conclusion it was shown that hs-CRP is related with asthma severity and ACT, and hs-CRP is a potential sensitive marker which reveals the severity and the control of asthma. © 2011 SEICAP.