Summary This study investigated whether osteoporosis and its treatment may affect periodontal condition in elderly women. The findings highlighted that women with osteoporosis had a higher chance to present severe periodontitis than women with normal bone mineral density (BMD), particularly those who were not treated for osteoporosis. Introduction This study investigated whether osteoporosis increases the frequency and severity of chronic periodontitis in elderly women and evaluated the influence of vitamin D and osteoporosis treatment in the periodontal condition. Methods In this cross-sectional study, elderly women were selected among 1266 subjects evaluated for lumbar spine and proximal femur bone mineral density (BMD) using dual energy X-ray absorptiometry. Sociodemographic, clinical characteristics, and complete periodontal examination were recorded. Serum 25-hydroxyvitamin D levels were measured by chemiluminescence. Results Forty-eight elderly women with normal BMD and 86 with osteoporosis were selected. Women with osteoporosis presented higher frequency of sites with clinical attachment level ≥6 mm ( p  = 0.003) and gingival recession ≥3 mm ( p  = 0.002) than those with normal BMD and were more than twice as likely to present severe periodontitis (odds ratio (OR) = 2.49, 95 % CI 1.14 to 5.43). Osteoporotic women who were not treated for the condition had more chance to present severe periodontitis (OR = 3.16, 95 % CI 1.28 to 7.82) than those who did use bisphosphonates (OR = 2.04, 95 % CI 0.85 to 4.89). Among the participants who presented low levels of vitamin D, those with osteoporosis exhibited a higher chance to present severe periodontitis than those with normal BMD ( p  = 0.027), but the association between vitamin D levels and osteoporosis was not statistically significant after adjustment ( p  = 0.198). Conclusions Elderly women with osteoporosis have a greater chance to present periodontitis, with higher severity than those with normal BMD. Osteoporosis treatment provides protection for periodontitis.