Catheter-associated urinary tract infection (CAUTI) is the leading cause of hospital-acquired infections in hospitalized patients in medical and surgical wards, but it is still commonly underdiagnosed in critically ill patients despite a higher device usage rate. The most commonly employed diagnostic criteria for such diagnosis come from the Infectious Disease Society of America and Centers for Disease Control and Prevention National Health Safety Network surveillance definition. It is surprising that no separate diagnostic criteria of CAUTI exist, for the critically ill patients – though these patients are of a different class of patients' altogether, due to decreased immunity, existence on multiple organ supports, and invasive lines, and an inability to communicate with a clinician. In this review, we highlight the difficulties in applying the available guidelines to diagnose CAUTI in critically ill patients. We also suggest an algorithm for the diagnosis of CAUTI in these patients.