Objective: Oxidative stress is the main pathogenetic mechanism in bladder cancer among many other causes. We aimed to investigate whether a potential relationship exists between bladder cancer and the activities of paraoxonase (PON1) and arylesterase (ARE) enzymes. Material and methods: The study included 56 patients with bladder cancer, and 57 healthy individuals. The relationships between enzyme activity and tumour grade, stage, muscular invasion and tumour size were evaluated. For statistical analysis, One-Sample Kolmogorov-Smirnov, Independent-T, ANOVA and Post-Hoc Bonferroni tests were used. Results: Serum levels of PON1 and ARE enzymes, and total cholesterol were significantly lower in bladder cancer group. While other lipid parameters were similar in both the patient and the control groups. Levels of ARE were positively correlated with lipid parameters except for HDL cholesterol. Conclusion: Our results showed that decreased serum PON1 and ARE enzyme activities are related with tumour load and recurrence. Further studies with larger samples are needed to confirm predictive role of enzymatic activities of PON1 and ARE in the diagnosis and prognosis of bladder cancer.