Several urinary markers for transitional cell carcinoma have been investigated, including urine cytology, bladder tumor antigen, autocrine motility factor receptor and fibrin degradation products. Unfortunately, they have poor overall sensitivity. The United States Food and Drug Administration have recently approved nuclear matrix protein (NMP 22) for the detection of occult or rapidly recurring disease after transurethral resection of bladder tumor. The objective of the current study was to assess the sensitivity of NMP 22 for the detection of bladder carcinoma, as well as to correlate the NMP 22 values with multiplicity of tumor, tumor size, configuration, stage and grade respectively. A total of 78 patients (38 with bladder cancer) provided a urine sample which was divided into appropriate aliquots for each of urine cytology and NMP 22. Comparative results demonstrate a clear superiority of NMP 22 in bladder cancer detection (52.6% vs 31.6% sensitivity), while specificity was in favor of urine cytology (100% vs 82.5%). For superficial tumors, sensitivity was 78.5% for NMP 22 and 41.6% for cytology and for invasive cancers, sensitivity was 90% for NMP 22 and 60% for cytology. Urinary NMP 22 levels were significantly correlated with tumor grade and were significantly higher in large tumors than small tumors. NMP 22 test results showed sufficient sensitivity in comparison with urine cytology for the detection of transitional cell carcinoma. However, we do not think that it is a useful tool as a substitute for endoscopic examination for the detection and surveillance in bladder cancer.