BACKGROUND: Numerous studies use fluorescent microscopy to obtain two-dimensional optical images of the morphology of nerve fibers in hypertrophic scars. In addition, current confocal microscopy studies have focused on normal, not pathological, cutaneous nerves. However, laser scanning confocal microscopy results in a three-dimensional structure of the nerve fibers. OBJECTIVE: To observe quantitative and morphological differences in nerve fibers from the proliferative and mature stage in hypertrophic scars using fluorescent and confocal microscopy. DESIGN, TIME AND SETTING: Neuropathological, comparison study was conducted at the Provincial Hospital Affiliated to Shandong University, China from June 2006 to July 2007. PARTICIPANTS: Specimens were selected from 30 patients undergoing scar restoration at the Provincial Hospital Affiliated to Shandong University of China at 1 month to 23 years following wound healing. The study comprised 20 males and 10 females. The scars were fibrous lesions, erythematous, tough, confined to skin lesions, did not exhibit ulceration or infection, exhibited telangiectasia, with or without itching and pain, and were not locally treated. Samples were equally assigned to two groups according to course of disease: proliferative group (< 6 months) and mature group (6-24 months). Control samples were collected from full-thickness skin from donor sites (n = 10).METHODS: Nerve fiber morphology was observed using fluorescent and confocal microscopy following immunofluorescence of the skin specimens. The microscopic images were semi-quantitatively analyzed to acquire a positive area ratio of neurofilament protein-positive nerve fibers. MAIN OUTCOME MEASURES: Morphology and positive area ratio of neurofilament protein/positive nerve fibers was measured.RESULTS: The positive area ratio of neurofilament protein-positive nerve fibers was significantly greater in the proliferative group compared to the normal control group (P < 0.05). Nerve fibers were irregularly distributed and exhibited local swelling, twisting, and disconnection. However, the positive area ratio of neurofilament protein-positive nerve fibers was significantly less in the mature group compared with the normal control group (P < 0.05). The nerve fibers were arranged in an orderly manner, with intact inner and stereoscopic structures similar to normal skin. CONCLUSION: Compared with mature scars, hypertrophic scars exhibited a greater number of nerve fibers, with more serious pathologies.