The aim of this study was to examine the histopathology of neobladder mucosa biopsy specimens obtained routinely as part of postsigmoidocolocystoplasty (SCP) follow-up.One hundred cases of SCP (mean age at surgery, 10.6 years) performed by the authors were examined for the presence of dysplasia or malignant changes in the mucosa of the neobladder using H&E and proliferating cell nuclear antigen (PCNA) staining.No dysplastic or malignant changes were identified in any case. Metaplasia was found in 5 cases and hyperplasia in 2. There were no major differences found on H&E and PCNA staining of specimens obtained after different periods of follow-up post-SCP; follow-up was short term (up to 5 years) in 44 cases, medium term (from 5 to 10 years) in 48 cases, and long term (over 10 years) in 8 cases. PCNA staining was significantly more intense in subjects who stopped regular bladder irrigations (Bl) post-SCP and in subjects in whom bladder stones developed (P <.05; Welch's t test), compared with subjects who continued Bl and subjects in whom bladder stones did not develop.After SCP, patients are advised to continue Bl. Regular biopsies should be part of routine follow-up, especially in subjects with bladder stones.