Retrospective cohort. To analyze and confirm the rates of postoperative complications of patients with hepatitis C virus (HCV) undergoing primary posterior lumbar fusion (PLF) and assess whether treatment of HCV before surgery reduces complications. HCV causes chronic disease, leading to increased risk of cirrhosis and chronic illness. Currently, there is a lack of research regarding whether the patient's HCV is a modifiable risk factor for postoperative complications after spinal procedures. The Mariner database was utilized to find patients from 2010 to 2018 undergoing PLF with active follow-up for a year. Cases involving same-day revision procedures and patients with a history of spine, infection, trauma, human immunodeficiency virus, hepatitis B, or neoplasm were excluded. Patients with a history of HCV diagnosis were identified and further stratified whether they had prior treatment using the national drug codes for antiviral, interferons, or ribavirin. Patients with HCV were matched with those without respect to age, sex, and comorbidity of burden. Outcome measured included 90-day medical complications, infection, readmission, and 1-year reoperation. There were 2,129 patients with HCV and 10,544 patients in the matched control group who underwent primary PLF. Out of the 2,129 patients, 469 (22.0.%) were treated with HCV medications before surgery. Patients with prior history of HCV had a significantly increased risk of wound complications (4.4% vs. 3.2%, odds ratio 1.56, 95% confidence interval 1.24-1.96, P =0.009), and infection (7.7% vs. 5.7%, odds ratio 1.26, 95% confidence interval 1.07-1.53, P =0.009) within 90 days of surgery. Patients treated before surgery did not have a difference in major ( P =0.205) or minor medical complications ( P =0.681) after surgery. Patients with prior history of HCV are at increased risk for many complications after surgery; however, this risk factor does not seem to be modifiable as the treatment group did not experience any improvement in postoperative outcomes. Level III.