OBJECTIVES:  Chronic hypoparathyroidism (HPTH) is a rare disorder that causes lower than normal levels of calcium in the blood due to insufficient levels of parathyroid hormone. Chronic HPTH can be inherited, associated with other disorders, or may result from neck surgery. Because no patient-reported outcome (PRO) measure specific to this condition was available to facilitate the evaluation of treatment, this study sought to create a PRO measure addressing HPTH symptoms. METHODS:  A literature review was conducted to identify symptoms of HPTH and any existing PRO measures appropriate to evaluate these symptoms. This review was followed by concept elicitation (CE) interviews involving 6 individuals with HPTH. Based on the results of the literature review and interviews, a draft item pool was developed and refined through two rounds of cognitive debriefing interviews with 6 additional patients (3 per round). RESULTS:  HPTH symptoms documented in the literature included muscle cramping/pain, tingling in limbs and extremities, muscle spasms, fatigue, joint/bone pain, heaviness/weakness in extremities, sleep disturbances, cognition issues, anxiety/fear, and sadness/depression. However, PRO measures appropriate to address these symptoms were not identified. Qualitative research participants included 11 females and 1 male with an average age of 49 years; the majority (10) of these participants were white. CE interview results were generally consistent with the results of the literature review; the most commonly reported symptoms included issues with cognition, often described as “brain fog” (n = 6), muscle cramping (n = 5), tingling (n = 5), and muscle spasms or twitching (n = 4). A total of 13 items comprise the HPTH Symptom Diary, which was found to be easily understood and relevant to the participants. CONCLUSIONS:  The HPTH Symptom Diary addresses the symptoms of HPTH important to patients. Further research is planned to develop a scoring algorithm and evaluate the measure’s psychometric properties.