We aimed to determine the incidence and distribution of neuroendocrine differentiated tumor cells in different categories of prostatic intraepithelial neoplasia (PIN). Methods: The presence of chromogranin-A in low grade and highgrade PIN (LGPIN and HGPIN) tissues was examined immunohistochemically. Results: A total of 55 specimens of LGPIN tissues, of which 10 were obtained during transurethral resection of the prostate (TURP) and 45 from biopsies, and 31 examples of HGPIN tissues (11 from TURP specimens and 20 from biopsies) were examined in this study. The expression rates of chromogranin-A were 34.5% (19/55) and 29% (9/31) in LGPIN and HGPIN tissues, respectively (p=0.075). Conclusions: The chromogranin-A neuropeptide is expressed to a similar extent in PIN tissues at various stages of differentiation. The data indicate that cells producing this neuropeptide have no specific role in the progress of PIN. The role of chromogranin-A expression in HGPIN cells needs further elucidation.