Introduction Duchenne muscular dystrophy (DMD) patients are at risk of developing conditions that can compromise their bone health, such as fractures and walking impairment. We aimed to assess bone mineral density as a function of the age of DMD patients. Materials and Methods The cross-sectional study included 48 participants. Bodyweight and height were collected to determine the height-for-age and BMI-for-age Z-scores. Lumbar spine (LS) and total body (TBLH) bone mineral density (BMD) measurements were performed with dual-energy X-ray absorptiometry. Height-for-age Z-scores (HAZ) of boys under 19 years-old were determined, and the BMD was adjusted for HAZ. Results The DMD patients' HAZ curve is on the left compared to the WHO standard. The older patients had lower LS-BMD (p = 0.012) and TBLH-BMD (p <0.001) Z-score values than younger patients. There was a moderate negative correlation between age and the LS-BMD Z-score (ρ = -0.49, p < 0.001), a strong negative correlation between age and the TBLH-BMD Z-score (ρ = -0.82, p < 0.001), and a moderate positive correlation between age and the TBLH-BMDHAZ (ρ = 0.43, p = 0.007). Conclusion For clinical evaluation DMD population, it is necessary to consider the variables related to height since the delay in linear growth may underestimate the BMD Z-scores. DMD patients have impaired linear growth, and older boys could have more severe bone morbidity.