OBJECTIVES: A large proportion of patients are non-adherent to anti-osteoporotic treatments within 12 months of initiation. In the health psychology literature, several behavioural models have been developed to explain non-adherence, most notably the Health Belief Model (HBM). Based on these, our study aimed to explore determinants of persistence (i.e., continuation) with anti-osteoporotic treatments. METHODS: A psychologist carried out face-to-face interviews with patients who had taken anti-osteoporotic treatment for 2 years. Interviews were based on a guide including questions on beliefs and experiences with osteoporosis and its treatment. Saturation was reached with 16 patients providing over 95% of information. Content analysis of interview transcripts was performed to highlight criteria that determine intentions regarding treatment continuation. RESULTS: Through patient interview analysis, determinants with an effect on persistence were categorized either as barriers or facilitators. While general health behaviour was identified in both type of determinants, barriers to persistence included: Disease perceived as non-severe ("osteoporosis is not a severe disease, perhaps not a disease at all"); Treatment side-effects ("there are side-effects, I suffer from allergies, I am hesitant to take treatment") and Constraints ("you have to take treatment every day"; "you have to wait 2 hours after dinner before taking treatment"). Facilitators included: Perceived benefits ("my treatment works, bone mineral density results are good"); Habit/maintenance ("I take my treatment because I am used to it, I do not question it") and Relationship with doctor ("I have confidence in my doctor"). CONCLUSIONS: Results are consistent with the health psychology models, in particular the HBM. They add new concepts to HBM. Results suggest that areas for improvement in persistence in osteoporosis lay in beliefs about disease and treatment efficacy, rather than treatment convenience.