Background. Chitotriosidase is an enzyme secreted by activated macrophages. This study aims to investigate the usefulness of circulating chitotriosidase activity as a marker of inflammatory status in patients with critical limb ischemia (CLI). Materials and Methods. An observational gender-matched case-control study was conducted on patients hospitalized with the primary diagnosis of CLI, as well as a control group. The control group consisted of healthy volunteers. Results. Forty-three patients were included in each group. Similar demographic characteristics (median age of 60-62 years and overweight) were observed in both groups. Chitotriosidase activity ranged from 110 nmol/ml/hr to 1530 nmol/ml/hr in the CLI group and from 30 nmol/ml/hr to 440 nmol/ml/hr in the control group; demonstrating significantly elevated values in the CLI group (p<0.001). Median plasma chitotriosidase activity was significantly elevated in smokers compared with non-smokers in both groups (p<0.05). However, this activity had higher values in CLI than in control subjects. Receiver operating characteristic (ROC) analysis was then performed in order to verify the diagnostic accuracy of chitotriosidase as an inflammatory biomarker in CLI.Conclusion. Circulating chitotriosidase is a test which can potentially be used for the monitoring of CLI patients without other inflammatory conditions. However, the interpretation of elevated values must take into account the inflammatory response induced by tobacco exposure.