Introduction: Urinary tract infections (UTI) include very different clinical conditions that can range from asymptomatic bacteriuria to acute pyelonephritis with sepsis. Cystitis is symptomatic infection of the bladder and pyelonephritis is the symptomatic infection of the kidney. The thiol-disulphide balance plays an important role in antioxidant defense, inflammation, immunological response, apoptosis and intracellular signaling mechanisms. The role and importance of thiol-disulphide balance has also been reported in some infectious diseases. We aimed to evaluate the relationship between thiol-disulfide homeostasis and UTI in patients with UTI.