AbstractBackground.Unintentional parathyroidectomy during thyroidectomy has been evaluated in a few studies. Moreover, the impact of the surgeon's experience and operative technique has not been evaluated. Our aim was to identify the incidence of unintentional parathyroidectomy during total thyroidectomy, its clinical consequences, and factors affecting its occurrence.Methods.We reviewed all total thyroidectomies during a 2‐year period. Patients were categorized into 2 groups: those with unintentional parathyroidectomy (parathyroidectomy group) and those without unintentional parathyroidectomy (no‐parathyroidectomy group).Results.Incidental parathyroidectomy occurred in 100 (19.7%) of the 508 patients. The groups were comparable in age, thyroid weight and pathology, operative time, surgeon experience (high/low volume), operative technique (suture‐ligation, LigaSure, or Ultracision), postoperative calcium, and transient hypocalcemia. No permanent hypocalcemia occurred. However, 11% of the parathyroidectomy group was men compared with 22% of the no‐parathyroidectomy group (p =.002).Conclusions.Unintentional parathyroidectomy, although common, has no clinical consequences. Unlike surgeon's experience and operative technique, patient sex was the only factor affecting its occurrence. © 2007 Wiley Periodicals, Inc. Head Neck, 2008