BACKGROUND: Fibrinogen is a risk factor for coronary heart disease (CHD), which is an acute-phase protein that is released when inflammation occurs. Fibrinogen is an essential component in the coagulation cascade and affects hemostasis, hemorheology, platelet aggregation, and endothelial function. D-dimers are inevitable products of fibrin degradation that results from thrombin activation; XIII activated factors and plasmin. AIM: This study was aimed to explore the accuracy of the fibrinogen/D-dimer ratio in predicting the slow flow phenomenon in CHD. METHODS: The study design is a diagnostic test with a cross-sectional design to assess the accuracy of the fibrinogen/d-dimer ratio in predicting coronary slow flow phenomenon (CSFP) in CHD. The study was conducted at the Department of Internal Medicine, Faculty of Medicine, Dr. Moh Hoesin Hospital, Palembang, Indonesia. The independent variables in this study were serum fibrinogen and D-dimer levels. Meanwhile, the dependent variable is sufferers of CHD with CSFP and regular flow. All data obtained from this study were analyzed using the SPSS version 20.0 for Windows program with a 95% confidence limit. RESULTS: This study showed that there was no difference in levels of fibrinogen and D-dimer in groups with CSFP and regular flow. Fibrinogen and D-dimer do not play a significant role in the CSFP process. The various etiological parts of this possible disorder still need further exploration and detail, ranging from the role of the renin-angiotensin-aldosterone system, the function of the autonomic nervous system, to the position of other endothelial factors. CONCLUSION: This study proves that fibrinogen has specific but not sensitive predictors of CSFP. The d-dimer value is also not accurate as a CSFP predictor. This study demonstrates that the fibrinogen / d-dimer ratio is not precise as a predictor of CSFP events.