CYP2C19 gene polymorphism combination with inflammatory cell ratios was significant in the prognosis of coronary heart disease. A cross-sectional analysis study, with 6 months follow-up on 142 patients with acute coronary syndrome. Patients were analyzed for CYP2C19 gene polymorphisms by real-time polymerase chain reaction (PCR) and complete blood count to determine inflammatory cell ratios and recorded cardiovascular events (CEs) after following up to 6 months. For 90-day CEs, CYP2C19 gene polymorphism (Hazard Ratio (HR): 1.965, 95 % Confidence Interval (CI): 1.012–3.814), the combination of a neutrophil and lymphocyte ratio (NLR) ≥ 2.982 (HR: 13.001, 95 % CI: 1.37–97.304) or a platelet to lymphocyte ratio (PLR) ≥ 162.42 (HR: 2.878, 95 % CI: 1.212–6.835) was independent predictors of CEs. For 180-day CEs, CYP2C19 gene polymorphism combination with NLR ≥3.02 (HR: 13.946, 95 % CI: 1.833–106.121) or PLR ≥160.38 (HR: 5.349, 95 % CI: 1.379–20.745) or monocyte to lymphocyte ratio (MLR) ≥ 0.3 (HR: 4.699, 95 % CI: 1.032–31.393) were independent predictors of CEs. NLR, PLR or MLR combined with CYP2C19 gene polymorphism were stronger independent predictors of cardiovascular events in patients with acute coronary syndromes compared to CYP2C19 gene polymorphism and inflammatory cell ratios separately. CYP2C19 polymorphism and high NLR was the strongest predictor of both CEs at 90 days and 180 days.