OBJECTIVES: To measure time to flap coverage after open tibia fractures and assess whether delays are associated with inpatient complications. DESIGN: Retrospective cohort study. SETTING: One forty level I and II trauma centers in Canada and the United States. PATIENTS/PARTICIPANTS: Adult patients (≥16 years) undergoing surgery for (1) an open tibia (including ankle) fracture and (2) a soft-tissue flap during their index admission between January 1, 2012, and December 31, 2015, were eligible for inclusion. EXPOSURE: Time from hospital arrival to definitive flap coverage (in days). MAIN OUTCOME MEASUREMENTS: The primary outcome was a composite of the following complications occurring during the index admission: (1) deep infection, (2) osteomyelitis, and/or (3) amputation. The primary analysis compared complications between early and delayed coverage groups (≤7 and >7 days, respectively) after matching on propensity scores. We also used logistic regression with time to flap coverage as a continuous variable to examine the impact of the duration of delay on complications. RESULTS: There were 672 patients at 140 centers included. Of these, 412 (61.3%) had delayed coverage (>7 days). Delayed coverage was associated with a significant increase in complications during the index admission after matching (16.7% vs. 6.2%, P < 0.001, number needed to harm = 10). Each additional week of delay was associated with an approximate 40% increased adjusted risk of complications (adjusted odds ratio 1.44, 95% confidence interval 1.13-1.82, for each week coverage was delayed, P = 0.003). CONCLUSION: This is the first multicenter study of flap coverage for tibia fractures in North America. Complications rose significantly when flap coverage was delayed beyond 7 days, consistent with current guideline recommendations. Because the majority of patients did not have coverage within this timeframe, initiatives are required to improve care for patients with these injuries. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.