Abstract Background Hypoparathyroidism (HPT) is a rare condition in which the parathyroid glands fail to produce enough parathyroid hormone (PTH) or the PTH produced lacks biologic activity. The aim of this study was to explore the patient experience of HPT. Methods Adult patients with HPT, recruited via a medical recruitment agency and the US hypoPARAthyroidism Association, participated in web-based, semi-structured, qualitative interviews that were audio-recorded and transcribed. Thematic analysis identified key symptoms and health-related-quality-of-life (HRQOL) impacts of HPT. Results Interviews were conducted with 16 patients with self-reported HPT for ≥ 12 months (15 females; age range 26-76 years). Key HPT symptoms reported included: fatigue (n=16, 100%), cognitive dysfunction (n=15, 94%), pain (n=15, 94%), tingling (n=14, 88%), muscles twitches/spasms (n=13, 81%), muscle cramps (n=12, 75%), temperature sensitivity (n =12, 75%), muscles weakness (n=12, 75%), cardiovascular issues (n =10, 63%), and eye problems (n= 9, 56%). Patients experienced intra-day symptom variability and unpredictability depending on treatment (Tx) regime. This erratic symptom experience hindered daily planning, and interactions with family/friends, resulting in emotional distress. Patients reported that HPT had a detrimental impact on their daily lives including impacts on physical functioning (n=11, 69%), sleep (n=10, 63%), daily activities (n=16, 100%), and work (n=13, 81%) as well as on relationships and social functioning (n=16, 100%). Fifteen patients (94%) reported emotional impacts; a key issue was the patient-perceived "invisibility" of HPT, specifically patients’ disease experience was often dismissed by family/friends as HPT is rare, with "no visible" symptoms. Patients also noted the burden of HPT management (e. g., Tx regimens, potential effects from long-term medication use). The need for constant vigilance associated with symptoms monitoring and medication use could be onerous. The absence of "at-home calcium monitoring" required patients to adhere to self-imposed "medication timetables": any deviations caused emotional distress as patients feared triggering a "calcium crash". Seven patients noted that Tx effects were not sustained throughout the day, leading to a re-emergence of symptoms as the day progressed. Patients reported that symptom reduction, improved Tx longevity and at-home calcium self-monitoring were key factors that could improve wellbeing and HRQOL. Conclusions The interviews provided valuable insights on the patient lived experience of HPT. Patients’ lives were significantly disrupted by their HPT symptoms regardless of Tx regime. This disruption was exacerbated by the unpredictability of symptoms which challenged patients’ ability to live their lives. These findings highlight the need for durable effective Tx for patients with HPT. Presentation: No date and time listed