Afeasibility study to evaluate the Chabner XRT® Radiation Bra (CIVCO Radiotherapy & Qfix, Coralville, IA, USA) as acustomised immobilisation device for patients with pendulous breasts undergoing radiotherapy was conducted. Atotal of 34patients with large pendulous breasts were fitted with the Chabner XRT® Radiation Bra during RT. Amixed-method questionnaire was administered to both radiation therapists (RTTs) and patients. RTTs evaluated the effectiveness of the bra in setup. Patients appraised its comfort level and ease of wearing. Setup reproducibility was evaluated based on adepartmental imaging protocol. Acute skin side effects were documented with photos and assessed using the Radiation Therapy Oncology Group (RTOG) classification. Of the patients, 27 (79.4%) completed the questionnaire. 23patients felt comfortable wearing the bra while 20 felt less exposed during treatment. Reproducibility was acceptable, with amedian (range) setup error (isocentre) of 0.0 cm (-0.6 to 0.7 cm; left/right), -0.1 cm (-0.5 to 1.2 cm; posterior) and 0.2 cm (-0.5 to 0.9 cm; inferior) achieved based on matched field borders on skin. However, repeated setups and imaging were required for 3patients due to large breast size (cups D-G; size 4-5). Minimal skin toxicity (grade0-1) was observed. No grade ≥ 2 was reported. 10RTTs completed the survey. Male RTTs (n = 4) were not confident in assisting patients with bra fitting. 8RTTs agreed that although it was difficult to reproduce the breast tissue for treatment, it helped patients to maintain the treatment position. Our study demonstrated the feasibility of using acustomised bra which provided optimal setup reproducibility while maintaining minimal skin toxicity and patient comfort, especially the value-added modesty felt among Asian women during their breast cancer radiotherapy.