Objective: Phalangeal quantitative ultrasound (QUS) measurements provide surrogate information on bone quality. The aim of the present study was to assess bone status by phalangeal QUS and by dual-energy x-ray absorptiometry (DXA), and to evaluate bone turnover in breast cancer (BC) women receiving aromatase inhibitors (AIs). Methods: Sixty postmenopausal BC women and 42 matched controls were recruited (mean age 61.64 ± 8.33 y). Amplitude-dependent speed of sound (AD-SoS), bone transmission time (BTT), Ultrasound Bone Profile Index, as QUS parameters, L1-L4 and femoral neck BMD by DXA were assessed at baseline and after 18 months; serum bone-specific alkaline phosphatase (BSAP) and C-telopeptide of type 1 collagen were measured at baseline, 9 and 18 months. Results: FRAX (without BMD) derived 10-years probability of major fractures and hip fractures were significantly associated with AD-SoS (r = −0.381, P = < 0.001 and r = −0.370, P < 0.001, respectively), Ultrasound Bone Profile Index (r = −0.434, P ≤ 0.001 and r = −0.409, P = < 0.001, respectively), BTT (r = −0.309, P = 0.002 and r = −0.340, P = 0.001, respectively). The median percent changes of AD-SoS (−3.71 [−5.38 to 0.11] vs −0.7 [−4.15 to 0.83], P = 0.02 respectively), BTT (−8.4 [−14.91 to −3.53] vs −1 [−5.72 to 3.75], P < 0.001 respectively) were significantly different between AIs users and controls. The same trend was observed for DXA measurements. BSAP and C-telopeptide of type 1 collagen significantly changed in AIs users. AD-SoS was associated with change of BMD at lumbar spine (β, 0.16; SE, 0.08; P = 0.04) and change of BSAP (β, −0.04; SE, 0.02; P = 0.04). Conclusions: Phalangeal QUS appeared a useful tool to evaluate bone quality in BC women on AIs.