Our study aims to retrospectively investigate neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and eosinophil-to-lymphocyte ratio (ELR) in patients infected with Clonorchis sinensis. This study analyzes a total of 151 patients with C. sinensis infections and 53 healthy control patients from our hospital. We found close relationships between the three candidate markers and the stages of C. sinensis infection-related biliary obstruction. The NLRs, PLRs and ELRs of patients with C. sinensis infections were significantly higher than those of healthy individuals; of those, ELRs showed the most superior diagnostic accuracy (sensitivity=62.9%, specificity=92.5%). Further, we constituted a logistic regression prediction model; applying two variables (age and NLR) with a sensitivity of 88.89% and a specificity of 83.78% in differentiating C. sinensis-related cholelithiasis from C. sinensis-untreated patients. Cancer antigen 19–9 (CA19–9) is a commonly used marker in the diagnosis of cholangiocarcinoma. Significant correlation was observed between NLR and CA19–9 in patients with C. sinensis–related cholangiocarcinoma (r=0.590, P=0.000). In the receiver operating characteristic analysis for separating C. sinensis–related cholelithiasis and cholangiocarcinoma, the cutoff value of PLR was 145.14 with a sensitivity of 65.62% and a specificity of 68.89%; the sensitivity of CA19–9 was 75.00% with a specificity of 77.78%. PLR showed acceptable efficiency to separate C. sinensis-related cholelithiasis from cholangiocarcinoma. In conclusion, all of the candidate markers (PLRs, NLRs and ELRs) may act as the valuable supplement in detecting C. sinensis infections and diseases.