Purpose The aim of this study is to investigate person-related, injury-related, activity-related and rehabilitation-related risk markers for not return to work among patients with acquired brain injury (ABI). Methods Retrospective data from the Quality register, WebRehab Sweden, on an ABI cohort of 2008 patients, was divided into two groups: those who had returned to work (n = 690) and those who had not returned to work (n = 1318) within a year of the injury. Results Risk ratio analyses showed that several factors were risk markers for not returning to work: personal factors, including being a woman, being born outside of Sweden, having a low education level, and not having children in the household; injury-related factors, including long hospital stay (over 2 months), aphasia, low motor function, low cognitive function, high pain/discomfort, and high anxiety/depression; activity-related factors, including low function in self-care, inability to perform usual activities, and not having a driver’s license; and rehabilitation-related factors, including being dissatisfied with the rehabilitation process and the attentiveness of the staff having limited influence over the rehabilitation plan, or not having a rehabilitation plan at all. Conclusion Several factors in different aspects of life were risk markers for not returning to work among patients with ABI. This suggests that rehabilitation and interventions need to address not only direct injury-related issues, but also person-related, activity-related, and rehabilitation-related factors in order to increase the patient’s opportunities to return to work.