In the correction of adult spinal deformities, the efficient placement of accurate pedicle screws is critical to overall procedural success. Custom 3D-printed drill guides have the potential to increase pedicle screw accuracy without increasing radiation exposure. No reports of iliac screw placement using 3D-printed drill guides have yet been published in the spine literature. A 72 year-old woman presented with progressively worsening axial back pain and radiographs showing a kyphoscoliotic lumbar deformity. A T10-pelvis spinal reconstruction was performed with the use of 3D-printed drill guides. For the iliac screws, an 8.5mm tap was passed through the drill guide to a depth of 90mm, followed by placement of 10.5mm x 90mm iliac screws. Total operative time from skin incision to closure was 3 hours and 56 minutes and estimated blood loss was 400 ml. The use of a 3D-printed drill guide in this case resulted in the fast and accurate placement of large spinal fixation screws in bilateral S1 and iliac trajectories. The S1 and iliac screws are of paramount importance as these screws support the entire spinal fixation construct and are subject to the greatest lever arm forces during patient movement. Custom drill guides appear to have utility in the placement of optimally sized sacral and pelvic fixation screws. The collection of further data is warranted to evaluate the accuracy of these guides in a larger series, as well as the effect of these guides on overall operative times and patient outcomes.