A high incidence of decreased bone mineral density (BMD) has been described in patients with severe congenital neutropenia (SCN). The objectives of the study are to describe changes in BMD in children with SCN treated with granulocyte colony-stimulating factor and evaluate the response to treatment with bisphosphonates in those who had osteoporosis. A prospective open-label study was performed evaluating BMD and metabolism in 9 Chilean patients with SCN, administrating bisphosphonates in those with osteoporosis. Follow-up ranged between 7 months and 3.5 years. Six out of 9 patients had reduced BMD on initial assessment: 3 had osteoporosis (z score <-2) and 3 had osteopenia (z score <-1). Four children presented vertebral fractures. Two presented osteopenia on follow-up without clinical symptoms. Five patients were treated with bisphosphonates, increasing their BMD z score (mean increase 1.2, range 0.27 to 2.62). z Score of hydroxyproline/creatinine ratios, which was elevated in 4 patients with osteoporosis, decreased during treatment (mean decrease 2.18, range 1.56 to 2.53). Four patients remodeled and reexpanded fractured vertebrae during treatment. No side effects of bisphosphonates were seen on follow-up. Osteoporosis is an important comorbidity in SCN patients probably due to increased bone resorption. Bisphosphonates seem to be an effective treatment for osteoporosis in these patients.