Purpose <p>To compare compensatory behaviors of the thoracic spine and pelvis between asymptomatic individuals and adult spinal deformity (ASD) patients with sagittal imbalance when lumbar lordosis changes.</p> Methods <p>The data of 625 asymptomatic adult volunteers and 219 ASD patients were retrospectively reviewed. Radiographic parameters, including the pelvic incidence (PI), cervical lordosis (CL), T1 slope, thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), sagittal vertical axis (SVA), thoracolumbar/lumbar (TL/L) curve, and lumbosacral curve, were measured via lateral whole-spine radiographs. The Oswestry Disability Index (ODI) and lumbar visual analogue scale (VAS) of each ASD were recorded.</p> Results <p>Propensity score analysis was conducted on the age, sex and PI of the patients to match the two groups. The number of patients analyzed in each group was 196. Compared with the asymptomatic population, the ASD population had a larger PT, smaller SS, smaller LL, smaller TK, larger CL, larger SVA, larger PI-LL, larger PT/PI, and smaller TK/PI (all <i>p</i> &lt; 0.001). In both the asymptomatic population and the ASD population, PI-LL was significantly correlated with PT and PT/PI (all <i>p</i> &lt; 0.001). In the poor compensation subgroup of ASD patients, the SVA was greater (<i>p</i> &lt; 0.001), the TL/L curve was greater (<i>p</i> = 0.016), the lumbar VAS was greater (<i>p</i> = 0.005), and the ODI was greater (<i>p</i> &lt; 0.001) than those in the good compensation subgroup.</p> Conclusions <p>Asymptomatic individuals and ASDs with sagittal imbalance have similar thoracic and pelvic compensative behaviors. During the reduction of LL in asymptomatic individuals and patients with ASD, thoracic and pelvic compensation can lead to a decrease in TK/PI and an increase in PT/PI. Good thoracic and pelvic compensation can alleviate the clinical symptoms of ASD.</p>