Introduction: Injuries of the recurrent laryngeal nerve (RLN) during thyroidectomy, although uncommon, can lead to major morbidity. Transection and permanent RLN injury are rare, however temporary neuropraxia and loss of signal (LOS) during intraoperative neuro-monitoring (IONM) are seen more frequently. The aims of this study were to identify factors associated with type I (segmental) and II (global) LOS of the RLN during thyroid surgery and to analyse time to recovery of vocal fold function. Materials & Method: This retrospective cohort observational study included 3806 patients (2924 female, 76.8%; 882 male, 23.2%) who underwent hemi- or total thyroidectomy in a tertiary referral centre in the period Jan 2015 – March 2021. Intermittent IONM was used routinely in all thyroid procedures studied. Regression analyses were used to determine factors associated with loss of signal and subsequent time to recovery. Results: RLN LOS occurred in 167 (2.7%) of 5983 nerves at risk during surgery. The rate of Type I LOS and Type II LOS per nerve at risk was 1.4% and 1.3% respectively. Compared with an indication of malignancy, indication of toxic nodule was associated with 96% increased odds of LOS independent of age and sex (P<0.001). The time to recovery was reduced for those who had a Type II LOS (median 4 weeks) compared to those who had a Type I LOS (median 8 weeks; p=0.04). Female sex and increasing age were each independently associated with a longer duration to return of vocal fold function. Conclusion: The time to recovery of RLN function is significantly reduced for patients who experience a Type II LOS. Toxic nodules are at increased risk of LOS compared to malignant nodules, and female sex and age are each significantly associated with a longer time to recovery.