Abstract Background Distal transradial access (dTRA) has been increasingly accepted as an alternative to the transradial access (TRA) for coronary angiography (CAG) and/or percutaneous coronary intervention (PCI). Although the dTRA has been significantly associated with better patient comfort, shorter haemostasis time, and fewer vascular access-related complications, such as haematoma and proximal radial artery occlusion (pRAO), it has also been associated with an increased risk of distal radial artery occlusion (dRAO). Purpose The aim of the present study was to investigate whether the 6-Fr thin-walled sheath was superior to the conventional radial sheath with respect to the incidence of distal radial artery occlusion (dRAO) at 24 h after CAG and/or PCI via dTRA. Methods A prospective, single-centre trial of patients who were randomized to undergo CAG and/or PCI with either a 6-Fr thin-walled sheath or a 6-Fr conventional sheath. The primary endpoint was the incidence of dRAO at 24 h postoperatively, as evaluated by Doppler ultrasound. The second endpoints included the puncture success rate, puncture time, the incidence of pRAO, pain during the sheath placement, and other vascular-associated complications. Results A total of 620 patients were included in the study. The mean age of the patients was 66.6± 9.7 years (median age 69.0 years [interquartile range 60.0- 74.0 years]), and 66.3% were men. The baseline patient and procedural characteristics were similar between the two groups. For the primary endpoint, the incidence of dRAO at 24 h after the procedure was 1.0% (3/314) in the thin-walled sheath group and 3.6% (11/306) in the conventional sheath group (RR= 0.266, 95%CI= 0.075-0.943, P= 0.027) according to the intention-to-treat (ITT) analysis. For secondary endpoints, the incidence of pRAO was 0.3% (1/314) in the thin-walled sheath group and 2.3% (7/306) in the conventional sheath group (P= 0.029). No significant difference was observed between the thin-walled sheath and the conventional sheath groups regarding the puncture success rate (92.4% vs. 92.5%, P= 0.952). The severity of pain experienced during the sheath placement was similar between the two groups (VAS 2 vs. 2 P=0.426). Other secondary endpoints, including procedural outcomes and other puncture-related outcomes and access-related complications, were not significantly different between the two groups. Conclusion A thin-walled sheath can reduce the incidence of early-term dRAO in patients who underwent CAG and/or PCI via the dTRA.The primary endpoint of the trial