Purpose: The purpose of this study was to measure the serum CRP levels and its significance in monitoring prognosis of the periapical infections. Materials and Methods: Serum samples were collected from 60 patients with periapical infections & from 30 healthy controls. Serum CRP levels were determined by using ultrasensitive turbidimetric immunoassay analyzer. After 7 days of treatment, patients were recalled to re–evaluate the serum CRP by the same procedure. Results: In patients with periapical infections, the pre and post treatment CRP levels were statistically highly significant except Chronic Apical Periodontitis & Periapical cyst. Conclusion: This study shows that Serum CRP levels were elevated in response to Periapical infections and also reduced significantly after treatment. The prompt treatment of these periapical infections helps to prevention of heart diseases which may result because of the elevated Serum CRP levels.