Abstract Background: There is some evidence from experimental studies that long-chain n-3 and n-6 fatty acids may be able to modify early skin carcinogenesis, but whether this applies in the general population is not known. Methods: We investigated associations between serum polyunsaturated fatty acid concentrations and p53 expression in normal skin, as a biomarker of early UV-induced carcinogenesis, in an unselected sample of Australian adults. Participants in the Nambour Skin Cancer Prevention Trial provided a dorsal hand punch biopsy which was used for immunohistochemical assessment of p53 immunoreactivity. Cross-sectional associations with serum fatty acid concentrations were analyzed in 139 participants, adjusting for confounding variables including skin phenotype, past sun exposure, and smoking status. Results: There was an inverse association, showing a dose–response relationship, between total n-3 fatty acid serum concentrations and p53 immunoreactivity in the whole epidermis and the basal layer. This was particularly due to eicosapentanoic acid and docosahexanoic acid concentrations. There was no evidence for increased p53 immunoreactivity in participants with relatively high serum n-6 fatty acid concentrations. The ratio of n-3 to n-6 fatty acid concentrations was not associated with p53 immunoreactivity. Conclusion: These results add to growing evidence that long-chain fatty acids may be able to modify early skin carcinogenesis. Impact: The prospect that increased intake of n-3 fatty acids could help prevent skin cancer is attractive. Cancer Epidemiol Biomarkers Prev; 20(3); 530–6. ©2011 AACR.