Malignant melanoma is the most lethal form of skin cancer. Although preclinical studies have shown that n-3 polyunsaturated fatty acids (PUFAs) are beneficial for prevention of melanoma, the molecular mechanisms underlying the protective effects of n-3 PUFAs on melanoma remain largely unknown. In the present study, endogenously increased levels of n-3 PUFAs in the tumor tissues of omega-3 fatty acid desaturase (fat-1) transgenic mice was associated with a reduction in the growth rate of melanoma xenografts. This reduction in tumor growth in fat-1 mice compared with wild-type controls may have been associated, in part, to the: i) Increased expression of E-cadherin and the reduced expression of its transcriptional repressors, the zinc finger E-box binding homeobox 1 and snail family transcriptional repressor 1; ii) significant repression of the epidermal growth factor receptor/Akt/β-catenin signaling pathway; and iii) formation of significant levels of n-3 PUFA-derived lipid mediators, particularly resolvin D2 and E1, maresin 1 and 15-hydroxyeicosapentaenoic acid. In addition, vitamin E administration counteracted n-3 PUFA-induced lipid peroxidation and enhanced the antitumor effect of n-3 PUFAs, which suggests that the protective role of n-3 PUFAs against melanoma is not mediated by n-3 PUFAs-induced lipid peroxidation. These results highlight a potential role of n-3 PUFAs supplementation for the chemoprevention of melanoma in high-risk individuals, and as a putative adjuvant agent in the treatment of malignant melanoma.