The role of oxyphil cells (OxC) in primary hyperparathyroidism (PHPT) still remains controversial. Historically, they were believed to be involuted cells. However, they could play an important role in hormone secretion. The clinical behavior of OxC-rich adenomas and preoperative PHPT localization tests have been widely studied. The aim of this study is to analyze the implications of OxC in PHTP.