Introduction: Osteogenesis imperfecta (OI) is a genetic disorder resulting in increased bone fragility due to defective collagen synthesis. Biphosfonates have been used in children with OI. Herein, we aimed to present clinical and laboratory features of the patients with OI and to evaluate response to biphosphonate therapy. Materials and Methods: The data of 21 patients with OI were evaluated retrospectively and clinical classification was made. Age, gender, auxological data, bone mineral density (BMD), and bone fragility before and after therapy were evaluated. Efficacy of alendronate and pamidronate on the bone density were compared. Results: Of the 21 patients, 12 were male (57.1%), 9 were female (42.9%) and median age was 5.64 years. According the Sillence classification, 10 patients were classified as type I, 9 cases as type III, and 2 cases as type IV. Diagnoses were made by multiple fractures (10 cases), pathological sole fracture (5 cases), blue sclera with history of fracture (2 cases), maternal OI, blue sclera, and decreased BMD (1 case), bone deformity, family history, and blue sclera (1 case). Pamidronate (13 cases) and alendronate (8 cases) were given as medical therapy. Basal DEXA z-score increased from -4.00 at baseline to -2.80 after 12 months of therapy (p<0.001). When the two therapy models were compared, there was no statistical difference. After one year of therapy, height SDS increased from -2.55 to -1.74 (p=0.433), and weight SDS increased from -1.79 to -0.51 (p=0.042). Annual fracture frequency decreased significantly from 2.14 to 0.62 per year (p<0.001). Conclusions: Three monthly pamidronate or daily alendronate therapy is effective to reduce clinical symptoms and annual fracture rate. Both biphosphonates enhance BMD safely without remarkable side effects. However, duration of therapy and possible side effects in the long run are still unclear and further research in larger groups is necessary. © The Journal of Current Pediatrics, published by Galenos Publishing.