Background: Low vitamin D levels are a risk factor for osteoporosis. In the Northern hemisphere, a high frequency of low vitamin D levels has been detected. The correction of this deficit is associated with a lower fracture risk. Aim: To measure serum vitamin D levels in postmenopausal women with low bone mineral density. Material and methods: 25-hydroxyvitamin D levels were measured in 40 postmenopausal women aged 50 to 74 years old, with a spine bone mineral density of less than 2 standard deviation of the values for young individuals. Serum calcium, phosphorus and calcium dietary intake were also measured. Results: Mean serum 25-hydroxyvitamin D levels were 32.2 ± 12.5 ng/ml. No correlation between vitamin D levels and other measured variables was observed. Using a cutoff value of 15 ng/ml, two women had low 25-hydroxyvitamin D levels. Conclusion: In this sample of postmenopausal women, vitamin D deficiency was infrequent (Rev Méd Chile 2001; 849-52).