We present the case of a 28-year-old female Rett syndrome patient with low bone mass and a recent fracture who was successfully treated with teriparatide. Bone mineral density and microarchitecture substantially improved after treatment. Rett syndrome (RTT), an X-linked progressive neuro-developmental disorder caused by mutations in the methyl-CpG-binding 2 (MECP2) gene, has been consistently associated with low bone mass. Consequently, patients with RTT are at increased risk of skeletal fractures. Teriparatide is a bone-forming agent for the treatment of osteoporosis that has demonstrated its effectiveness in increasing bone strength and reducing the risk of fractures in postmenopausal women, but, recently, its positive action has also been reported in premenopausal women. We present the case of a 28-year-old female RTT patient with low bone mass and a recent fracture who was successfully treated with teriparatide. Both bone mass measured by DXA and microarchitecture assessed by high resolution peripheral computed tomography (HR pQCT) were substantially improved after treatment.