Background: Aromatase inhibitors (AIs) are associated with profound estrogen deprivation resulting in reduced bone mineral density (BMD). Periodontal diseases and tooth loss are associated with estrogen withdrawal and decreased systemic BMD. Little is known as to the impact of AIs on oral health. To investigate oral health as a breast cancer (BCA) survivorship concern, a prospective study was initiated to determine the prevalence of periodontal diseases in postmenopausal early stage (I-IIIA) BCA survivors on adjuvant AI therapy. Baseline assessments are presented here. Methods: Women within 6 months of initiating adjuvant AI for hormone receptor positive BCA were eligible to participate in this study of serial assessments of oral health. A control group of women without BCA and not on AI underwent parallel assessments. Periodontal status was evaluated by the following established dental techniques; (1) periodontal pocket depth (PD), (2) number of teeth with bleeding on probing (BOP), (3) the number of teeth with clinical attachment loss (CAL). Questionnaires regarding socio-demographic and dental utilization were administered to all participants. Linear regression modeling was used to analyze the outcomes. Results: The study met its target accrual of 58 postmenopausal women; 29 with BCA on AI and 29 controls. Demographics were similar regarding age, education, income level, frequency of dental visits, and dental insurance status across both groups. Baseline assessments demonstrated no differences in PD (2.0 mm vs. 2.0 mm; p < 0.95) or the number of teeth (26.6 vs 26.1; p< 0.39). Interestingly, the AI group had significantly more sites of BOP (27.9 vs 16.7; p < 0.02), and higher CAL (5.2 mm vs 4.0 mm; p < 0.01) than did controls. In linear regression analysis adjusted for income, AI use increased CAL by 1 mm (95% CI: 0.15 -1.88). There was also a trend for decreased CAL in subjects with incomes over $75,000 per year (p< 0.06). Conclusions: This first investigation of the periodontal status of women initiating adjuvant AI therpay identifies this population to have signs of increased risk for periodontal disease. Serial oral health assessments are being conducted to assess AI therapy and periodontal changes over time. Clinical trial information: NCT01693731.