OBJECTIVE. To determine the proportion of cytologically correctly diagnosed pathohistologically proven low-grade urothelial carcinomas and the proportion of false- negative diagnoses. To perform the rescreening of available cytological specimens in order to determine possible failures in interpretation, taking into account diagnostic criteria of the Paris System for Reporting Urinary Cytology. ORGANIZATION OF STUDY. Retrospective comparative study. RESPONDENTS AND METHODS. The study included respondents who were diagnosed with the pathohistological diagnosis of low-grade urothelial lesion in the period from 2006 to 2015, provided that in the period of no longer than one year prior the patohistological verification they had had a cytological urine analysis. Exclusion criteria were as follows: inadequate cytological/pathohistological findings and the existence of histologically proven high-grade lesion in the period of one year before or after a verified low-grade lesion. RESULTS. In case of respondents with pathohistologically proven low-grade urothelial carcinoma, negative findings were diagnosed in 82.1 % cases, atypia in 0.9 % cases, papillary proliferation findings in 2.9 % cases, dyskaryotic cells were found in 4.7 % cases, suspicious lesion in 4.7 % cases and urothelial carcinoma in 4.7 % cases. The proportion of cytologically correctly diagnosed low-grade urothelial carcinoma was 17 %, if a precise diagnosis implies papillary proliferation findings, dyskaryotic and suspicious cells findings and urothelial carcinoma findings, as they require further urological analysis. The proportion of false-negative findings was 83 % (if atypical cells findings are interpreted as negative findings). Rescreening of the available cytological specimens showed no omissions in interpretation. CONCLUSION. Cytomorphological diagnostics of low-grade urothelial carcinoma are very demanding; therefore even experienced cytologists are not able to reliably identify most of the low-grade urothelial carcinomas using available criteria.