OBJECTIVE To evaluate the impact of pubertal induction with testosterone on bone health, body composition, and motor function in boys with Duchenne muscular dystrophy (DMD) receiving long-term glucocorticoid. METHODS A retrospective, observational, pre-post study investigating the impact of testosterone therapy on bone mass accrual, vertebral fracture incidence, body composition, motor function, and quality of life in boys with DMD. All those boys aged ≥14 years, on chronic steroid therapy, who had delayed puberty, and were receiving oral testosterone or oral and then transitioned to intramuscular testosterone, to complete virilization, were included. Prior/concomitant zoledronic acid use was included. The primary outcome was lumbar spine areal bone mineral density (BMD LS). RESULTS Puberty was induced, using oral testosterone undecanoate in 16 individuals, 10 of whom had transited to intramuscular testosterone at time of assessment. Median age at testosterone onset was 14.5 years (range 14-17.7). Median duration of testosterone therapy was 2.5 years (range 1.0-4.5). There was statistically significant increase in median BMD LS (0.523-0.700, p < 0.001) and median annualized percentage change of BMD LS (-1.34 to +10.08%, p < 0.001), with median Tanner stage 4 at evaluation (range 2-4). Ten of 14 assessed had no progression in vertebral fractures. Fat mass index (FMI) standard deviation score (SDS), lean body mass index (LBMI) SDS, and percentage change of FMI and LBMI were statistically unchanged. Cardiac function remained stable. Motor function in non-ambulatory individuals with Egen Klassifikation scores improved in 7 of 8. CONCLUSIONS Testosterone for delayed puberty acted as an adjunct to bisphosphonates to increase bone density and stabilize vertebral fracture in most boys with DMD.