BACKGROUND: Transradial intervention (TRI) may impair digital perfusion with hand dysfunction as a result. However, the effect of TRI on digital perfusion has never been investigated, including the influence of variations of the collateral arterial network and the effect on hand dysfunction. METHODS AND RESULTS: We investigated the effect of TRI on digital perfusion by laser Doppler perfusion imaging. Laser Doppler perfusion imaging was performed at baseline, during radial access, TR band application, and at discharge. We compared tissue perfusion of the homolateral thumb (access site) with the contralateral thumb (comparator) during radial access as primary outcome. The hand circulation was assessed with angiography. Upper extremity function was evaluated with the validated QuickDASH questionnaire at baseline and follow-up. A significant reduction of tissue perfusion was observed during radial access and TR band application in the homolateral thumb (-32%, -32%, respectively) and contralateral thumb (-34%, -21%, respectively). We detected no perfusion difference between the homolateral and contralateral thumb during radial access (217; interquartile range, 112-364 versus 209; interquartile range, 99-369 arbitrary flux units; P=0.59). Reduced perfusion of the thumb during radial access was not associated with incompleteness of the superficial palmar arch ( P=0.13). Digital perfusion improved at discharge, though it remained below baseline levels (homolateral -11% and contralateral -14%). Hand dysfunction at 18 months was not associated with TRI-induced perfusion reduction ( P=0.54). CONCLUSIONS: TRI is safe. Digital perfusion is reduced in both hands during radial access and TR band application but is not associated with future loss of hand function and variations of the arterial hand supply.