In vitro studies have implicated neuroendocrine differentiation in the development of hormone resistant prostate cancer following administration of androgen blockers. Studies on clinical material are equivocal. We wished to understand the significance of neuroendocrine differentiation in our large and well-characterised cohort of clinically localised prostate cancer, treated conservatively. Immunohistochemical expression of chromogranin-A was assessed semi-quantitatively on tissue samples of 806 patients in a tissue microarray approach. The correlation of expression with 10-year prostate cancer survival was examined. Multivariate analysis including contemporary Gleason score was performed and sub-group analysis of early hormone treated patients was also undertaken. Chromogranin-A expression correlated with high Gleason score (χ 2=28.35, p<0.001) and early prostate cancer death (HR=1.61, 95 %CI01.15-2.27, p<0.001). In univariate analysis, NE differentiation correlated significantly with outcome (HR=1.61, 95 % CI 1.15-2.27, p<0.001) However in multivariate analysis including Gleason score, chromogranin-A expression was not an independent predictor of survival (HR=0.97, 95 %CI00.89-1.37, p=0.87). Although chromogranin-A expression was higher in patients with early hormone therapy (χ 2=7.25, p= 0.007), there was no association with prostate cancer survival in this sub-group (p=0.083). Determination of neuroendocrine differentiation does not appear to have any bearing on the outcome of prostatic carcinoma and does not add to the established prognostic model.