The regular consumption of long-chain omega-3 polyunsaturated fatty acids (LCO3-PUFAs) results in general health benefits. The intake of LCO3-PUFAs has been reported to contribute to bone metabolism. We aimed to investigate the relationships between dietary intakes of LCO3-PUFAs and bone mineral density (BMD) in Spanish women aged 20-79 years old. A total of 1865 female subjects (20-79 years old) were enrolled, and lumbar (L2, L3, L3 and total spine), hip (femoral neck (FN), femoral trochanter (FT) and Ward's triangle (WT)) bone mineral density (BMD) were measured by dual energy X-ray absorptiometry (DXA). Dietary intakes of total energy, calcium, vitamin D, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and n-6 fatty acids (linoleic acid (LA) and arachidonic acid (AA)) were assessed by a self-administered food frequency questionnaire (FFQ). Spearman's rank correlations between LCO3-PUFAs and BMD were estimated. Partial correlations controlling for age, weight, height, dietary calcium, vitamin D, menopausal status and energy were calculated. A multiple regression analysis was computed to assess significant associations with BMD in this population. After adjustment for potential confounding factors, there were positive correlations between ALA, EPA and DHA intake and BMD. According to the WHO diagnosis criteria for osteoporosis, in this population of normal and osteopenic women, the dietary intake of ALA was also significantly associated with BMD at the hip. In normal women, the dietary intake of DHA was also significantly associated with BMD at the lumbar spine. No significant associations between LCO3-PUFAs and BMD were detected in the lumbar spine of osteopenic or osteoporotic women. The dietary intake of LCO3-PUFAs was positively associated with BMD in Spanish women at both the hips and the lumbar spine. We highlight that the intake of LCO3-PUFAs is not significantly associated with BMD in osteoporotic women; however, the intake of LCO3-PUFAs seems to be positively associated with BMD at both the hips and the lumbar spine in normal and osteopenic women.