A heterodigital neurovascular reverse-flow flap island flap for extensive pulp defects is described. A dorsolateral flap from the middle phalanx, based on the digital artery, is harvested from the adjacent uninjured finger. The common digital artery between the injured finger and the donor finger is ligated and transected just before its bifurcation. At this point the 2 converging branches of the digital arteries can be entirely mobilized as a continuous vascular pedicle for the flap. The vascularization is now supplied by reverse flow through the proximal transverse digital palmar arch of the injured finger; to provide sensation, the dorsal branch of the digital nerve from the donor finger must be included in the flap. This technique is indicated for large pulp defects with bone exposure of index and middle finger pulps, which are important for sensation.