The tragic death of an anaesthetic trainee driving home after a series of night shifts prompted a national survey of fatigue in trainee anaesthetists. This indicated that fatigue was widespread, with significant impact on trainees' health and well-being. Consultants deliver an increasing proportion of patient care resulting in long periods of continuous daytime duty and overnight on-call work, so we wished to investigate their experience of out-of-hours working and the causes and impact of work-related fatigue. We conducted a national survey of consultant anaesthetists and paediatric intensivists in the UK and Ireland between 25 June and 6 August 2018. The response rate was 46% (94% of hospitals were represented): 84% of respondents (95%CI 83.1-84.9%) contribute to a night on-call rota with 32% (30.9-33.1%) working 1:8 or more frequently. Sleep disturbance on-call is common: 47% (45.6-48.4%) typically receive two to three phone calls overnight, and 48% (46.6-49.4%) take 30 min or more to fall back to sleep. Only 15% (14.0-16.0%) reported always achieving 11 h of rest between their on-call and their next clinical duty, as stipulated by the European Working Time Directive. Moreover, 24% (22.8-25.2%) stated that there is no departmental arrangement for covering scheduled clinical duties following a night on-call if they have been in the hospital overnight. Overall, 91% (90.3-91.7%) reported work-related fatigue with over half reporting a moderate or significantly negative impact on health, well-being and home life. We discuss potential explanations for these results and ways to mitigate the effects of fatigue among consultants.