Background: Research shows that fear of cancer recurrence (FoR) is a significant concern for women who have been treated for breast cancer. Clinical prognosis has little to do with recurrence fears and the self regulatory model of illness may explain individual differences in FoR. Despite some evidence that patient beliefs impact the experience of FoR, it is not clear from the current literature how illness and medication beliefs and treatment side effects relate to FoR among women who are taking aromatase inhibitors as adjuvant endocrine therapy to prevent cancer recurrence.Methods: A total of 153 post-menopausal women with early stage breast cancer completed a postal survey. Analyses were conducted to examine the relation between FoR and illness and medication beliefs, treatment side effects, demographic factors and anxiety and depression and to identify which of these factors would be most strongly associated with FoR in a regression model. Results: All illness beliefs apart from personal control over illness were associated with FoR as were beliefs about the necessity of aromatase inhibitors and concerns about their use. Although being unemployed, having higher scores on anxiety and depression and reporting more side effects of medication were associated with FoR, only illness and medication beliefs were significantly correlated with FoR in the regression model. The overall model accounted for 61% of the variance in FoR scores (p<.001). Conclusions: The findings highlight the significant associations between beliefs about illness and medication and fear of recurrence among women taking aromatase inhibitors. Based on findings, it appears that women with higher FoR may be balancing a tension between beliefs about the necessity of taking aromatase inhibitors against the belief that this treatment may not prevent recurrence. Findings also indicate that women with higher FoR are more likely to report more symptoms from breast cancer.