AIM: To investigate any relationship between choroid thickness (CTh) and coronary artery disease (CAD), particularly in its earlier stages before clinically evident. METHODS: The study was performed in two institutions, in B. C. Hospital and B. E. R. Hospital. The ophthalmological examinations and coronary angiograms were performed in B. C. Hospital. The analysis of the coronary angiograms including determination of Gensini scores (Gsc) were conducted in B. E. R. Hospital. The study group comprised 136 eyes (in 68 patients) with documented CAD and 120 healthy eyes (in 60 healthy control subjects). Following measurements of macular thickness and retinal nerve fiber layer, CTh of both eyes was assessed by enhanced depth imaging optical coherence tomography. During the analyzes, main outcome measures were CTh in CAD patients and healthy subjects, correlation between CAD severity-based on Gsc- and CTh in CAD patients. RESULTS: The study group comprised 68 patients (136 eyes) with documented CAD and 60 healthy controls (120 eyes) without any CAD or CAD equivalent disease. In all measured areas (central fovea, nasal and temporal area), CTh was thinner in all Gsc subgroups of CAD patients compared to the healthy group. Even in the lower Gsc subgroup, CTh was significantly thinner compared to the healthy group. A multivariate logistic analysis was conducted and lower CTh in temporal-1000 regions were significantly associated with an increased likelihood of early CAD [OR: 0.812 (CI: 0.762, 0.944), P : 0.032]. Receiver operating characteristic (ROC) curve analysis disclosed CTh at temporal 1000 < 259 μm may predict early CAD (Gsc < 11) with 82% sensitivity and 58% specificity (AUC: 0.68, P < 0.001, CI: 0.65-0.76). CONCLUSION: Even in its earlier stages, CAD has inverse relationship with CTh, which may give oppurtunity for CTh measurement to predict CAD at earlier phases.