OBJECTIVES. To evaluate the reproducibility of cytological assessment of red cell morphology of the two observers cytologists and the level agreement between them and the observer from the biochemical laboratory. To determine a degree of correlation among observers based on the amount of erythrocytes and urinary protein, as well as pH. STUDY DESIGN. A cross-sectional study. PARTICIPANTS AND METHODS. The study included 100 respondents who provided a urine sample once or in three consecutive days at the Department of Clinical Pathology, University Hospital Center Osijek and the Department of Pathology and Cytology at General Hospital Slavonski Brod. The samples were processed in cytocentrifuge, native colored and assessed by two cytologists. The samples were processed in a centrifuge in the laboratory and the morphology was estimated on at least 100 erythrocytes by the observer. Test strip was used to determine pH, the number of red blood cells and the amount of protein. RESULTS. There is a statistically significant positive medium strong association in estimating red cell morphology between the two observers cytologists ( = 0.689). Between each observer cytologist and observer in the laboratory there is a statistically significant positive, but weak correlation ( = 0.472), respectively ( = 0.444). The amount of red blood cells is a factor that significantly affects the reliability of the assessment. Reliability increases with the number of red blood cells ( = 0.689 for one cross, = 0.974 for four crosses). The extreme pH values negatively affect the degree of the correlation among the observers. CONCLUSION. The degree of the correlation between the two cytologists in assessing red cell morphology belongs to the category of good agreement, the method is reproducible. Lower values of agreement between cytologists and observer in the 9. Summary 26 laboratory, which are the result of different methodology of sample preparation, where the observer in the laboratory requires the assessment of the minimum of 100 red blood cells, suggests the need for auditing and standardization of methods of processing urine samples in cytology laboratories.