BACKGROUND: Treatment expectations form a fundamental component of the self-regulatory model of health behavior, which defines such cognitions as illness perceptions. Unrealistic and/or unhelpful treatment expectations have been linked to detrimental clinical and work outcomes in those with persistent low back pain. However, research of this nature has rarely focused on the influence of 'significant others' (spouse/partner/close family member). OBJECTIVE: To provide an in-depth examination of the treatment expectations of the 'significant others' of individuals who have become unable to work due to persistent low back pain, highlighting how significant others may influence recovery and work participation outcomes for such individuals. PARTICIPANTS: A convenience sample (n=18) of work disability benefit claimants and their significant others were recruited from two settings in the North of England. METHOD: A qualitative research design was employed, and semi-structured interviews based on the chronic pain version of the Illness Perceptions Questionnaire-Revised were conducted with claimants and their significant others. Interview data were analysed using template analysis. RESULTS: It was found that significant others expected a substantial reduction or complete removal of pain in order for treatment to be considered successful. The pursuit of diagnostic tests was important in validating such expectations, and there was continued scepticism of treatments already undertaken or offered as an alternative. Like the individuals affected, significant others believed that a correct diagnosis had not yet been received, which led to a continued delay in return to work. CONCLUSIONS: This study demonstrates that significant others have similar unrealistic and/or unhelpful treatment expectations to those widely reported by individuals with persistent low back pain, and could further reinforce such illness perceptions and serve as wider psychosocial obstacles to recovery and continued work participation.