BACKGROUND: The use of large-bore (LB) arterial access and guiding catheters has been advocated for complex percutaneous coronary intervention. However, the impact of LB transradial access (TRA) and transfemoral access (TFA) on extremity dysfunction is currently unknown. METHODS AND RESULTS: The predefined substudy of the COLOR (Complex Large-Bore Radial PCI) trial aimed to assess upper and lower-extremity dysfunction after LB radial and femoral access. Upper-extremity function was assessed in LB TRA-treated patients by the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire and lower-extremity function in LB TFA-treated patients by the Lower Extremity Functional Scale questionnaire. Extremity pain and effect of access site complications and risk factors on extremity dysfunction was also analyzed. There were 343 patients who completed analyzable questionnaires. Overall, upper and lower-extremity function did not decrease over time when LB TRA and TFA were used for complex percutaneous coronary intervention, as represented by the median Quick Disabilities of the Arm, Shoulder, and Hand score (6.8 at baseline and 2.1 at follow-up, higher is worse) and Lower Extremity Functional Scale score (56 at baseline and 58 at follow-up, lower is worse). Clinically relevant extremity dysfunction occurred in 6% after TRA and 9% after TFA. A trend for more pronounced upper-limb dysfunction was present in female patients after LB TRA (P=0.05). Lower-extremity pain at discharge was significantly higher in patients with femoral access site complications (P=0.02). CONCLUSIONS: Following LB TRA and TFA, self-reported upper and lower-limb function did not decrease over time in the major-ity of patients. Clinically relevant limb dysfunction occurs in a small minority of patients regardless of radial or femoral access. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03846752.