A total of 200 patients attending a haematuria clinic in Quebec, Canada were studied. These patients were considered to be low risk for urothelial cancer as they were non-smokers, with no significant occupational risk factors, history of previous malignancies or radiotherapy or cyclophosphamide exposure. Approximately 15% of patients with atypical cytology were found to have tumours. When atypical cytology was analysed as a positive result, the sensitivity, specificity, positive predictive value and negative predictive value of the test were 50%, 90%, 17% and 98% respectively. 'The use of urine cytology in non-visible haematuria is currently recommended by the American Urological Association guidelines, but the British Association of Urological Surgeons/Renal Association guidelines in the UK do not recommend the routine use of cytology. While this study is small and can only be of limited use in determining the correct management strategy for this condition, it would appear to support the British guidelines. GPs should therefore observe these guidelines, with initial investigation in primary care of MSU to exclude infection plus measurement of renal function, albumin:creatinine ratio and blood pressure, followed by referral to secondary care for further investigation.'