Background: Fusion at the craniovertebral junction is performed to treat instability of the upper cervical spine and occiput. The literature consists exclusively of case series in which complication rate and avoidance are variably addressed. Objective: To describe the rates of various complications encountered during craniocervical fusions and discuss preoperative and perioperative strategies useful for risk reduction. Methods: A computerized search of PubMed for literature on craniocervical fusion and other upper cervical fusions was performed. Keywords used in the search included: occipitocervical fusion, odontoid screw, atlantoaxial fusion, with and without complications, anterior fixation, lateral mass screw, transarticular screw, halo, vertebral artery injury, and odontoid fracture. References were limited to studies on human subjects. Other sources were identified from the reference lists of relevant publications. Results: Twenty-two reports described data derived from 2274 procedures analyzed for complications. The most commonly encountered perioperative complications were related to instrumentation failure after nonunion with rates as high as 7% during occipitocervical fusion and 6.7% during atlantoaxial fusion. Other commonly encountered complications included injury to the vertebral artery (1.3%-4.1% during placement of C1-C2 transarticular screws, most commonly in the case of high-riding vertebral artery), dural tears, and wound infection. Conclusion: Occipitocervical or atlantoaxial fusion procedures can be performed with low morbidity. Safety is enhanced with appropriate preoperative assessment of anatomic variants and preparation for perioperative management of complications.