Background: As multiple myeloma (MM) negatively affects patients’ (pts) health-related quality of life (HRQoL), assessment of patient-reported outcomes (PROs) in addition to clinical outcomes is important. Teclistamab (tec; JNJ-64007957) is an off-the-shelf bispecific antibody that redirects CD3+ T cells to mediate T-cell activation and subsequent lysis of BCMA-expressing MM cells. Initial results from the pivotal cohort of the phase 1/2 MajesTEC-1 study demonstrated that tec was well tolerated with encouraging efficacy in pts who received ≥3 prior lines of treatment (LOT; including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 antibody). Here we report PROs from this cohort. Methods: Pts (aged ≥18 years) had documented RRMM (International Myeloma Working Group criteria), progressive/measurable disease, and had previously received ≥3 prior LOT; prior anti-BCMA treatment (tx) was not allowed. Pts received weekly subcutaneous tec at the recommended phase 2 dose (1.5 mg/kg with step-up doses of 0.06 and 0.3 mg/kg). PROs were assessed at screening and every even cycle (cycles 2–8 reported here) using the EORTC QLQ-C30 (range: 0–100; higher scores indicate better global health status [GHS] but greater symptom severity [symptom scales]) and the EuroQol 5-dimensional descriptive system (visual analog scale [VAS] range: 0 [worst imaginable health state] to 100 [best imaginable]). Tx effect was assessed by a mixed-effects model with repeated measures; the proportion of pts with meaningful improvement was defined as a change ≥10 points. Time to worsening was determined using the Kaplan-Meier estimate. Results: A total of 110 pts were included (median follow-up: 7.8 mos). Overall PRO compliance rates were high (baseline [BL]: 85–90%; cycles 2–8: 80–94%). Tec improved overall HRQoL as evidenced by improvements in GHS scores (cycles 2–8) and reduction in pain (-4.2 [cycle 2] to -15.1 [cycle 8]; Table), with no overall change in physical functioning and fatigue. The proportions of pts with meaningful improvements from BL at cycle 8 were GHS: 50%; physical functioning: 35%; pain: 65%; fatigue: 73%; 50% of pts reported meaningful improvement in their overall health (VAS). Median time to improvement from baseline was ̃1.5 months (with nausea/vomiting and fatigue taking longer to improve), while median time to worsening (all symptoms) ranged from 2 months to not estimable. Conclusions: Consistent with clinical outcomes, pts treated with tec reported rapid, clinically meaningful improvements in HRQoL. Clinical trial information: NCT04557098.