Background: Processed nerve allografts are commonly utilized for clinical nerve repair. Nonetheless, chronic discomfort and ongoing loss of function have been linked to allograft failure, which has a high documented occurrence rate. Aim: One year after the first operation, the current study sought to evaluate the unsuccessful allograft repair in a sensory human nerve by immunohistochemical and histological investigation. Methods: Processed nerve allografts were used for repair in four participants who had suffered superficial radial nerve injuries. Clinical findings at the follow-up visit revealed significant neuropathic pain and no reinnervations of sensory nerves. The removal of the unsuccessful transplant and histologic and immunohistochemical analyses came next. Collagen content, lymphatic and blood vasculature, and the neurofilament network were measured in the middle of the specimens. Results: Histologic examination revealed increased fibrosis, fatty degeneration, and disordered growth of nerve fibers. Additionally, a recognizable pattern was observed in the microvascular network of the allografts, with an increase in microvessels and no alteration in the lymphatic vasculature. Conclusion: Within the constraints of the research, the current study finds that loss of microvascular and physiologic architecture is linked to human allograft failure. More clinical research is necessary to evaluate the interaction between angiogenesis, lymphangiogenesis, and axonal regeneration, nevertheless, in order to better understand the mechanism underlying the failure of human nerve allografts.