Aims We evaluated the accuracy of medical coders in distinguishing the aetiology of urinary tract infection according to clinical documentation. Methods The clinical documentation of patients coded as having had a hospital-acquired urinary tract infection from January to June 2020 at two Melbourne hospitals were assessed for community or hospital acquisition. Results We found that 48.89% of cases were inaccurately categorised as hospital-acquired, due to insufficient detail in clinical documentation. Risk factors for hospital-acquired urinary tract infection were present in at least 30% of correctly categorised cases. Conclusions Clinical documentation is not filled out with sufficient detail or in a timely enough manner for clinical coders to distinguish between hospital or community origin.