The aim of the work was to investigate the bone mineral density (BMD) in middle-aged male patients with both childhood-onset (CO) and adulthood-onset (AO) adult growth hormone deficiency (AGHD). In this retrospective cross-sectional study in a major medical center in China, dual X-ray absorptiometry was performed in 50 male AGHD patients (average age was 35.2±9.8 years) and 50 age- and BMI-matched non-athletic healthy men. BMD was compared between AGHD patients and controls. Compared with healthy controls, AGHD group had significantly decreased IGF-1 (p1<0.001) and IGF-1 SDS (p1<0.001). Serum testosterone levels were significantly lower in AGHD patients (p1<0.001), mainly in AO AGHD patients (p3<0.001). The BMD of the femoral neck, trochanter, femoral shaft, total hip, and lumbar spine were significantly lower in all AGHD patients compared with healthy controls (all p1<0.05), especially in CO AGHD patients (all p2<0.05). Multiple stepwise linear regression indicated AGHD was negatively correlated with BMD at each site (β<0, p<0.05). Additionally, serum testosterone level was an independent influencing factor of BMD of the femoral neck (β=0.256, p=0.018) and lumbar spine (β=0.219, p=0.040). BMD was significantly reduced in AGHD patients, especially in CO AGHD patients. Our data suggested that the status of growth hormone deficiency and testosterone level were important for maintaining of bone mineral density in middle-aged male patients with AGHD.