Background: Alopecia areata is an autoimmune disorder that results in unpredictable hair loss. It is characterised by autoreactive T cells around the hair follicles that release pro-inflammatory cytokines and adversely affect the anagen hair follicle cycle. There is evidence to suggest that hair follicle melanocytes are targeted by T lymphocytes, but major pigment cell autoantigens remain unidentified. Current therapies are predominantly corticosteroids and immuno-modulating agents, but these are often ineffective and new targeted therapies are especially required for children, people with longterm patchy alopecia, and individuals with alopecia totalis or alopecia universalis. Aims: The aims of this project were 1) to describe the Sheffield alopecia areata patient cohort in terms of its demographic and clinical details; and 2) to identify and characterise novel melanocyte autoantigens using phage-display technology in order to aid a detailed understanding of the pathogenesis of alopecia areata, which is required to inform the development of new treatments. Methods: Patient recruitment and assessment; phage-display technology to identify melanocyte autoantigens; radioligand binding assays to confirm immuno-reactivity of patient sera to identified autoantigens; ELISAs to characterise autoantibody binding sites and subclass; antibody functional assays. Results: Biopanning of a melanocyte peptide phage-display library with alopecia areata patient sera, identified several novel melanocyte autoantigens, including OCA2-encoded P protein, the melanocortin 1 receptor (MC1R), and glycoprotein non-metastatic melanoma protein b. The immunoreactivity of each of these potential autoantigens was tested in radioligand binding assays against 48 alopecia areata patient sera and was detected in 8 (16.7%), 21 (43.8%), and 10 (20.8%) patient serum samples, respectively. Further analysis of MC1R antibodies indicated that their binding sites were on extracellular domains of the receptor, were of the IgG1 subclass and, in two patients, adversely affected the function of the MC1R. Conclusions: Phage-display technology was useful for identifying novel autoantigens in alopecia areata. Further work is required to ascertain if the novel autoantibody targets are also the targets of autoreactive T lymphocytes in alopecia areata patients.