Pituitary adenomas without clinically active hypersecretion are summarized under the term nonfunctioning pituitary adenomas (NFPAs). Since there are no specific serum markers, the differential diagnosis and treatment imply special difficulties. Aim. To investigate the immunohistochemical and radiological features of NFPAs and assess the granins — chromogranin A (CgA), secretogranin II (SgII), secretoneurin (Sn) as immunohistochemical markers of NFPAs. Matherial and methods. 50 pituitary adenomas excised surgically were immunostained to reveal pituitary hormones, ki-67, CgА. SgII, Sn. All patients underwent MRI, invasive growth was estimated due to J.Hardy classification (1973). Results. 24 (51,1%) were gonadotropic tumors, 12 (25,5%) — null cell adenomas. Immunopositivity for ACTH was determined in 6 cases (12,7%), for GH in 5 (10,6%) cases, for PRL in 4 (8,5%). The median level of ki-67 was 2% (min. — 0.5%, max. — 7%). The CgA, SgII, Sn immunopositivity was found in 83, 93,6, 85,1% respectively, being more expressed in gonadotropinomas and null cell adenomas. Invasive growth was detected in 28 (44%) cases, among the invasive adenomas 22 tumors were giant. CgA expression is adverse prognostic factor, area under the curve (AUC) with 0,705. We did not find any correlation between ACTH-, STH-, CgII- and Sn- immunopositivity, ki-67 and invasive growth. Conclusions. Our work shows that a majority of NFPAs are truly secreting adenomas with significant numbers comprising potentially hazardous cortico- and somatotropinomas. CgA, SgII and Sn have a high expression in most of the NFPAs.