Neonates undergoing emergency abdominal surgery frequently require a stoma; closing this stoma with a second operation is an essential part of recovery. Timing of closure varies. Optimal timing is unclear and would be best resolved through a randomised controlled trial; such a trial is likely to be challenging. To determine if it is feasible to conduct a clinical trial comparing 'early' versus 'late' stoma closure in neonates. Mixed methods comprising three parallel workstreams incorporating: a clinician survey, prospective observational cohort study, parent interviews, focus groups, database analyses and consensus meeting. Specialist neonatal surgical centres across the United Kingdom. Neonatologists, neonatal surgeons, neonatal dietitians and neonatal nurses who care for neonates with stomas. Neonates with recent stoma, their parents and the clinicians looking after them. Three existing, overlapping clinical databases. One hundred and sixty-six professionals from all 27 neonatal surgical centres completed the survey: 6 weeks was the most common target time for stoma closure across clinical scenarios, although there was wide variation. Timing of closure was influenced by nutrition, growth and stoma complications. The prospective cohort study enrolled 56 infants from 8 centres. Infants were mostly preterm with necrotising enterocolitis or intestinal perforation. Clinicians identified extreme preterm gestation and clinical conditions as reasons for not randomising babies into a hypothetical trial comparing early and late stoma closure. Parents and healthcare professionals identified that comparator arms needed more clinical flexibility in relation to timing of stoma closure. Analysis of existing databases revealed wide variation in current timing of stoma closure in neonates and identified approximately 300 eligible infants for a trial per annum in the United Kingdom. A trial of 'early' compared to 'late' stoma closure in neonates is feasible and is important to families and health professionals. The population of eligible babies in the United Kingdom is sufficient for such a trial. Challenges centre around lack of equipoise in certain scenarios, specifically: extremely preterm infants; infants waiting too long for stoma closure in the 'late' comparator; and logistical issues in closing a stoma at a trial-allocated time. These challenges are addressable by incorporating flexibility based on gestation at birth, communicating that both trial arms are standard practice and valid treatment options, and providing resources, for example, for operating lists. We recommend the following population, intervention, comparator and outcome as a starting point to inform future trial design. Population: neonates with stomas (excluding those with a fixed treatment pathway). Intervention: stoma closure at 6 weeks and after 32 weeks post conceptual age. Comparator: expectant management with stoma closure undertaken when the clinical team determines is best for the infant. Primary outcomes: weight gain/growth or length of hospital stay. This study is registered as IRAS Project ID 278331, REC Reference 20/LO/1227. This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR128617) and is published in full in Health Technology Assessment; Vol. 28, No. 71. See the NIHR Funding and Awards website for further award information.