Background Care left undone is a worldwide problem for both the quality of health care and the safety of patients. In surgical nursing, care left undone is a critical issue arising from the intensive pace of work, invasive procedures and the pressure for efficiency. Previous knowledge about care left undone in surgical contexts is missing. Objective To describe care left undone and its relationship to nursing and organisational characteristics in the surgical wards of regional and central hospitals in Estonia. Methods A cross‐sectional study with an online questionnaire took place from June to October of 2018. The target population (N = 570) consisted of nurses working in the surgical wards of two regional and three central hospitals at the time of the study. The data were analysed using descriptive statistics and Fisher's exact test. The open‐ended questions were analysed with deductive content analysis. Results Nursing care in the surgical wards was reported as having been left undone sometimes or often by 88% of the nurses. Most often, the documentation and evaluation of care plans (33%) were reported as undone and most rarely, disinfection measures were left undone (5%). Nurses with a shorter employment history left care undone more frequently, and when the number of patients per nurse increased, the amount of care left undone increased as well. More than half of the participants (59%) considered work organisation to be the cause of care left undone. Conclusions Work organisation and staffing in surgical wards require more attention at the management level, as nursing care left undone occurred to a significant degree in the investigated wards, and more than half of the nurses considered work organisation to be the reason for care left undone.