['Bone marrow transplantation (BMT) recipients are at risk of bone mass impairment and skeletal morbidity. We investigated bone status with quantitative ultrasound (QUS) technique in children and adolescents with hematological diseases before and after BMT.', 'Phalangeal QUS measures for amplitude-dependent speed of sound (AD-SoS) and bone transmission time (BTT) were obtained in 144 hematological patients (81M, 63F; 11.6+/-5.2 years); forty two were evaluated before BMT and 102 after allogeneic or autologous BMT. Bone parameters were expressed as Z-scores based on age-sex-matched normal controls.', 'Mean BTT Z-score was reduced in subjects after BMT compared to patients before BMT (M, -0.35+/-1.04 vs. 0.70+/-1.11, P<0.001; F, -0.60+/-1.23 vs. 0.23+/-1.17, P<0.05). Females and males with hormone deficiencies showed reduced BTT Z-scores when compared with subjects without hormone defects (M, -0.52+/-1.0 vs. 0.05+/-1.17, P<0.05; F, -0.50+/-1.27 vs. -0.19+/-1.26; P=0.06). AD-SoS and BTT Z-scores were reduced in 15 subjects with fractures and/or avascular osteonecrosis compared to patients without bone events (-1.52+/-1.7 vs. -0.41+/-1.32 and -0.85+/-1.19 vs. -0.10+/-1.18; both Ps<0.05). Bone event cumulative incidence was 4 times greater in subjects who suffered from chronic GVHD.'] Does quantitative ultrasound detect bone impairment after bone marrow transplantation in children and adolescents affected by hematological diseases?