Endovascular occlusion of hemorrhagic dissecting aneurysms of the vertebral artery (VA) is not possible when the posterior inferior cerebellar artery (PICA) originates from the dissecting aneurysm or when the contralateral VA provides inadequate collateral blood flow to the distal basilar circulation. The authors introduce a VA-PICA bypass with radial artery interposition graft and aneurysm trapping as an alternative approach and describe 2 cases in which this bypass was used to treat hemorrhagic dissecting VA aneurysms. The VA-PICA bypass is performed via a standard far lateral approach. An end-to-side anastomosis between the radial artery graft and the PICA at the level of the caudal loop is performed first, and an end-to-side anastomosis is performed between the V(3) segment and the proximal end of the radial artery graft. A 56-year-old woman harbored a hemorrhagic dissecting VA aneurysm incorporating the origin of the PICA. Endovascular treatment failed, with aneurysm refilling on follow-up angiography. A 65-year-old man had a hemorrhagic dissecting VA aneurysm and a hypoplastic contralateral VA. Both patients were treated with the VA-PICA bypass and aneurysm trapping, with adequate filling of the PICA territory in the first patient and both the PICA territory and the basilar circulation in the second patient. Vertebral artery-PICA bypass with radial artery interposition graft and subsequent trapping of the dissected VA segment is an alternative to occipital artery-PICA and PICA-PICA bypass for the treatment of hemorrhagic dissecting VA aneurysms that are not suitable for endovascular occlusion.