INTRODUCTION: Although hair loss (alopecia) is a benign disorder, it can negatively affect patient's self-esteem, self-image, and overall quality of life. Linzagolix is an oral GnRH antagonist being developed at full and partial suppression doses with and without hormonal add-back therapy (ABT) for treatment of uterine fibroid-related symptoms. Alopecia was previously reported with other GnRH antagonists. METHODS: PRIMROSE 1 and 2 are two randomized, double-blind, placebo-controlled phase 3 trials investigating the efficacy and safety of linzagolix 100 mg and 200 mg once daily, +/- ABT in the treatment of uterine fibroids for 52 weeks. RESULTS: Up to week 24, alopecia was reported in total of five subjects (0.5%) in the pooled safety analysis set (N=1037). There was a similar incidence in the placebo (two subjects; 1.0%), 100 mg (one subject; 0.5%), and 200 mg+ABT groups (two subjects; 1.0%), and no reports in the 100 mg+ABT or 200 mg groups. Four of the cases resolved. For one subject (200 mg+ABT group) mild alopecia had not resolved. For this subject, the study drug was continued, and no concomitant therapy was administered for the alopecia. Up to week 52, one (0.1%) subject in the 200 mg+ABT group reported alopecia, which resolved. None of the cases led to treatment discontinuation. No subjects reported alopecia during the post-treatment follow-up. CONCLUSION: Hair loss (alopecia) was rarely observed in the PRIMROSE trials of linzagolix in the treatment of uterine fibroids.