This study aimed to assess the impact of the use of an additional iliac bone graft on functional and radiographic results after thoracic spine arthrodesis with pedicle screws in patients with adolescent idiopathic scoliosis. Participants were divided into two groups: a control group that received only local bone (n=19) and a second group that, in addition to this procedure, received an iliac graft (n=22). The evaluations were performed on preoperative, immediate postoperative, and last follow-up (mean 29.7 months; minimum 12 months). Radiographic evaluations included the loss of correction and the presence of nonunion. The functional outcome was evaluated using the Scoliosis Research Society-30 questionnaire. Surgical complications and the presence of iliac donor site pain were also described. There were no significant differences between groups in the pseudoarthrosis rate, loss of correction over time, and quality of life. We concluded that the addition of bone graft from the iliac yielded no benefit in terms of the fusion rate and functional outcomes. The appropriate facetectomy, bed preparation, and filling with a local bone graft must be adequate to achieve an adequate fusion on surgical treatment of adolescent idiopathic scoliosis.