The reported incidental prostate cancer prevalence rates at radical cystoprostatectomy cover a range from 4 to 60 %. We investigated the influence of the histopathological work-up on prostate cancer prevalence rates. We identified 114 patients who had undergone cystoprostatectomy for bladder cancer between 2000 and 2012. Complete histopathological assessment was defined as follows: (i) complete embedding of the prostate gland, (ii) sectioning of 15 or more prostate sections, and (iii) processing as whole mount slides. Prostate cancer prevalence rates derived from complete and incomplete histopathological assessments were compared. The overall prostate cancer prevalence rate was 59.6 %. A mean of 14.4 macroscopic tissue sections (thickness 3-5 mm) were sectioned. Sectioning ≥15 sections resulted in a prostate cancer detection rate of 75 %, compared to 42.6 % when sectioning <15 sections (p < 0.001). Complete embedding yielded a prostate cancer detection rate of 72.3 and of 23.1 % for partly embedded prostates (p < 0.0001). Prostate cancer was detected in 68.8 % of the whole mounted samples and in 38.2 % of the samples sectioned as standard slides (p < 0.01); according to the criteria described by Epstein and Ohori, 44.1 % of the detected prostate cancers were clinically significant. The quality of the histopathological work-up significantly influences prostate cancer detection rates and might at least partially explain the highly variable reported incidental prostate cancer prevalence rates at cystoprostatectomy (CP). The high proportion of significant prostate cancer found in our series calls for a careful surgical approach to the prostate during CP.