Children with Medicaid may have difficulty accessing care for adolescent idiopathic scoliosis (AIS), a condition that may worsen with time. We conducted a study to determine whether patients with Medicaid present with a larger curve magnitude. We reviewed the cases of consecutive AIS patients treated with posterior spinal fusion (PSF) between 2008 and 2012. Children seen for second opinions were excluded. Medical records were evaluated to determine time from evaluation to determination for surgery, time from recommendation for surgery to actual procedure, and insurance status. Radiographs were reviewed to determine Cobb angle at initial presentation. Of the 135 patients who underwent PSF for newly diagnosed AIS, 39% had Medicaid insurance. Compared with private insurance patients, Medicaid patients presented with a larger mean (SD) Cobb angle, 57.2° (15.7°) versus 47.5° (14.3°) (P < .001), and had larger curves at time of surgery, 60.6° (13.9°) versus 54.6° (11.7°) (P = .008). There was no difference in wait time from the decision to undergo surgery to the actual surgery or in mean (SD) number of levels fused, 10.3 (2.2) for Medicaid patients versus 9.7 (2.3) for private insurance patients (P = .16). Compared with private insurance patients, Medicaid patients who underwent PSF for AIS had larger presenting Cobb angles and larger Cobb angles at time of surgery.