Objective: It is important to know the elapsed symptom-to-door (StD) time between the emergence of ST-elevation myocardial infarction (STEMI) symptoms and admission to the hospital in terms of the selection of appropriate treatment and prognosis. In this study, we aimed to assess the relationship between serum C-reactive protein (CRP) and StD time after STEMI.Methods: 436 of the patients admitted to our center with STEMI between August 2012-February 2013 (338 male, mean age, 63.9±12.8) were included in this prospective-observational cohort study. Blood samples were obtained from laboratory results of the first reference period. Patients were divided into four groups according to the duration of StD time [0-1. hour; group 1 (G1), 1-3. hour; group 2 (G2), 3-6. hour; group 3 (G3), 6-12. hour; group 4 (G4)]. Statistical analysis was performed via chi-squre test, ANOVA test, Pearson's correlation analysis and receiver operator charecteristic (ROC) analysis.Results: As the time progressed, an increase in CRP levels was observed. The difference among the means of the G1-G3 (p=0.002), G1-G4 (p<0.001), G2-G4 (p<0.001) and G3-G4 (p<0.001) groups was found to be statistically significant. There was a good correlation between the StD time and CRP levels (r=0.676). ROC analysis of the predictive value of CRP for the third hour was determined as 0.78 mg/dL, respectively (AUC was 0.824; 95% C.I. was 0.785-0.859; 73.9% sensitivity, 78.1% specificity).Conclusion: According to serum CRP levels after STEMI at hospital admission, StD time can be estimated.