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Objective: Smooth muscle fibres are found within thesuperficial lamina propria of urinary bladder (Muscularis Mucosa). Thesemuscle fibres of muscularis mucosa should be distinguished from themuscularis propria in cases with urothelial carcinoma, because the depthof infiltration affects prognosis and therapy modalities. The aim of thepresent study was to evaluate whether the presence of vascular plexus isa criterion for muscularis mucosa and to distinguish it from muscularispropria in urinary bladder biopsies and transurethral resectionspecimens. Materials and methods: Hematoxylin-Eosin andMasson-Trichrome stained slides of 54 cases with urothelial carcinomawere reviewed. Results: In all cases (100%), thick walledvessels were observed within the lamina propria of urinary bladder.Smooth muscle layer of lamina propria was seen in 48 of 54 cases(88.8%), and these smooth muscle fibres were co-existed with thickwalled vessels. In invasive urothelial carcinoma; thin smooth musclefibres and thick walled vessels were seen within the lamina propria in22 of 24 cases (91.7%). There were two cases (8.3%)including only vessels in small biopsies of invasive urothelialcarcinoma cases. In cases with non-invasive urothelial carcinoma; musclefibres of muscularis mucosa and vessels were found within the laminapropia in 26 of 30 cases (86.7%). In this group, muscle fibreswere not detected in 4 cases (13.3%). Conclusion:Muscularis mucosa can be detected histologically in urinary bladderbiopsies and TUR materials. We emphasize that the presence of vascularnetwork is a useful criterion to determine muscularis mucosa of urinarybladder, even in the absence of muscle fibres.