Urine cytology is the most useful technique for detecting either primary or recurrent neoplasms in the urinary tract. Although urine cytology is the traditional method of detecting these neoplasms, its diagnostic accuracy has been underevaluated because of low sensitivity. The cytologic interpretation of urinary samples is not an easy task, even with some expertise in this area, for many reasons. In low-grade urothelial carcinoma, no reliable or reproducible diagnostic cytologic criteria can be provided because of the lack of obvious cytologic features of malignancy, which is one of the main factors lowering its diagnostic accuracy. Many diagnostic markers have been developed recently to enhance its diagnostic yield, but the results have not been satisfactory. However, urine cytology plays a role in detecting high-grade urothelial carcinoma or its precursor lesions. It still shows higher specificity than any of the newly developed urine markers. Understanding the nature of urine samples and the nature of neoplasms of the urinary tract, recognizing their cytologic features fully, and using cytologic findings under appropriate conditions in conjunction with a detailed clinical history would make urine cytology a very valuable diagnostic tool.