Thrombomodulin [TM] is a surface glycoprotein involved in the regulation of intravascular coagulation that has been reported to be expressed in a variety of tumours including mesothelimas, endothelial vascular tumours, squamous carcinomas and transitional mesothelimas. This study was conducted to evaluate TM expression in a variety of urinary bladder carcinomas [Bilharzial and non-Bilharzial] using immunohistochemical techniques. Fifty eight bladder carcinomas were examined [20 were squamous cell carcinomas [SCC], 24 transitional cell carcinomas [TCC] and 14 adenocarcinomas]. Of these 58 cases, 26 were Bilharzial associated bladder cancer [BBC]. TM immunostaining was noticed in 24/26 [92%] of BBC compared to 50% in non-Bilharzial. In cases of SCC positivity for TM was 100% either Bilharzial or non-Bilharzial and the intensity of staining decreased with the grade of the tumour. In TCC, TM immunostaining was slightly higher in Bilharzial than in non-Bilharzial associated tumours, 80% compared to 71% respectively but, the intensity of sttaining increased with the grade of the tumour. Only 2 of the 14 adenocarcinomas of the bladder examined showed focal TM immunostaining in the areas of squamous cell differentiation. No explanation could be found for the predominance of TM expression in Bilharzial than in non-Bilharzial bladder cancer and so, long term studies onlarge number of cases may be able to explain such observation