To evaluate the thin-layer method in urinary cytology we have compared cytospin smears, filter and thin layer. Cellularity, cellular morphology and background were evaluated. Thin layer method in urinary cytology improve cell recovery and cell preservation, reducing background artefact. Cytohistologic correlations with thin layer method were better than with filter and cytospin; an higher capacity to detect low grade transitional cell carcinomas, frequently undiscovered by cytology, was demonstrated.