Residents play a crucial role in out-of-hours service. Their perceived readiness for out-of-hours service, however, remains underexposed. This national exploratory study assesses whether or not Dutch residents feel sufficiently prepared to provide out-of-hours service at the time of their first shift, and aims to identify factors influencing perceived readiness.An online questionnaire focussing on residents' working conditions was accessible from 21 September to 10 November 2015. Questions targeting perceived readiness for out-of-hours service were presented to all responding medical residents actively involved in out-of-hours service. Residents who felt sufficiently prepared were compared with residents who did not, exploring both individual characteristics and environmental factors.A total of 960 residents (mean age 32.5 years ±; 3.5, 72.4% female) from over 30 different medical specialties were included. Thirty-six percent of responding residents felt insufficiently prepared to provide out-of-hours service at the time of their first shift. Current junior status (p = 0.020), prolonged clinical experience prior to the first shift (p < 0.001), targeted training (p < 0.001), assessment of relevant skills and competencies (p < 0.001), and formal consequences following negative assessment (p = 0.001) were positively associated with perceived readiness.One-third of responding residents felt insufficiently prepared for their first out-of-hours shift. Our results emphasise the need for sufficient time to gain clinical experience as a new graduate, and underline the positive contribution of targeted training and assessment of skills and competencies relevant to out-of-hours service.