OBJECTIVES. To test the correlation between cytological and pathohistological diagnosis in patients with pathohistologically proven high-grade non-invasive urothelial carcinoma. To determine the proportion of cytologically accurately diagnosed pathohistologically proven high-grade non-invasive papillary urothelial carcinoma and flat lesions (carcinoma in situ) and the proportion of false negative cytological diagnosis. STUDY DESIGN. A retrospective cohort study. PARTICIPANTS AND METHODS. The study included 64 respondents who performed histopathological verification of high-grade non-invasive papillary lesions of urothelial epithelium or flat lesions (carcinoma in situ) from 2006 to 2015 with prior cytological urine screening. The cytological samples were sedimented, air-dried and fixed in 95 % alcohol and painted by May-Grünwald-Giemsi and Papanicolaou at the Department of Clinical Cytology, University Hospital Center Osijek. The histological findings were recorded at the Anatomy and Department of Pathological Judicial Medicine, University Hospital Center Osijek. The pathohistological diagnosis is based on biopsy or resection material fixed in formalin and embedded in paraffin blocks. RESULTS. In patients with pathohistologically proven high-grade non-invasive urothelial carcinoma, there is a correlation between cytological and pathohistological diagnosis. The rate of cytologically accurately diagnosed pathohistologically proven flat lesions was 11 / 12 of cases. The rate of citologically accurately diagnosed pathohistologically proven high-grade non-invasive papillary carcinoma was 31 (60 %) of cases. CONCLUSION. Cytology of voided urine revealed a total of 42 (66 %) high-grade non-invasive urothelial carcinoma, which assigns cytology a highly important position in the diagnosis of not only invasive but also non-invasive high grade carcinomas.