No previous study has compared the complications between anterior/posterior and transforaminal interbody fusions. We performed a retrospective analysis of 164 patients to compare the complications and associated predictive factors of the two techniques of circumferential lumbar fusion. Fifty-three had same-day anterior/posterior fusion (group 1), and 111 had transforaminal interbody fusion (group 2). Mean operating time (p < 0.0001) and hospital stay (p < 0.0001) was significantly longer for group 1 patients. Average blood loss was greater for group 1 patients (p < 0.01). Higher complication rates were found in group 1 patients (p < 0.004). Wound infection occurred more frequently in patients with adjunctive treatment (p < 0.04). Hospital stay was an independent predictor of complications in both groups. In group 1, body mass index was independently associated with complications. In group 2, both hospital stay and adjunctive treatment were predictive of complications. Transforaminal lumbar interbody fusion is the preferred technique because it is associated with shorter operating time, less blood loss, shorter hospital stay, and lower incidence of complications.