Secondary hormonal deficiency (SHD) is common in patients presenting with nonfunctioning pituitary adenomas (NFA). NFA can either stain for various hormones or be non-hormone staining on immunocytochemistry. To date, no study has assessed the association between staining pattern of NFA and pattern of SHD at presentation. The Halifax Neuropituitary Program has been prospectively collecting comprehensive data on all neuropituitary patients in the province of Nova Scotia, Canada since November 2005. For this study, we conducted a retrospective analysis of 167 consecutive patients with NFA who had undergone surgery in our centre and reviewed their pathology data including immunocytochemistry as well as hormonal profile at presentation. Of those, 72 (43.1%) did not stain for any pituitary hormone, 66 (39.5%) stained for a single hormone and 29 (17.4%) stained for multiple hormones. Of the single staining NFA, follicle stimulating hormone staining was the commonest, accounting for 28 (16.8%) of cases. A logistic regression analysis was conducted to identify any association between stating pattern and SHD correcting for age, gender and size of tumour at presentation. Our data showed that NFA which stained for multiple hormones were significantly less likely to cause SHD (OR = 0.26, CI 0.10.7; P <0.001) whereas there was no difference in SHD patterns in NFA with single vs. no hormone staining (OR = 0.98, CI 0.432.24; P =0.96). These novel data suggest that staining pattern in NFA is associated with SHD and raise the possibility of additional autocrine/paracrine factors that may cause SHD in these patients.