Food production in intensive farming systems can be unsustainable in several ways. Although hen egg is consumed worldwide as a very valuable and cheap source of protein, there is an evident lack of studies concerning the environmental performance of egg production. The European Union produces approximately 7 million tonnes of useable eggs per annum and Spain is one of the largest egg producers. In this work, Life Cycle Assessment (LCA) methodology was applied to analyse the environmental impacts of intensive egg production using as a model a Spanish farm with 55,000 laying hens, producing about 13 million eggs per year. High quality inventory data was obtained directly from this facility. The main factors involved in egg production were included (hen feed, water, electricity, transport, cleaning elements, packaging material, replacement of exhausted laying hens, wastes and gas emissions). Inventory data were analysed using the ReCiPe Midpoint (H) V1.12/Europe Recipe H, the ReCiPe Endpoint (H) V1.12/Europe Recipe H methods and the Greenhouse Gas Protocol V1.01/C02 eq (kg) by means of the LCA software package SimaPro v8. LCA results showed that, according to normalization results, natural land transformation was the most prominent category, followed by terrestrial ecotoxicity and freshwater ecotoxicity. The most important source of harmful environmental impacts in all the categories under assessment was the production of the hen feed and, to a lesser extent, the purchase of new laying hens to replace the old ones. On the contrary, water consumption and the employment of chemicals for cleaning barely influenced the impact. One aspect that was noteworthy was the beneficial effect on environmental impact produced by the sale of old laying hens for meat production, especially on the urban land occupation and metal depletion categories. Additionally, the carbon footprint of egg production was calculated and a value of 2.66 kgCO(2)eq per dozen eggs was obtained. Environmental improvement actions should be directed mainly towards optimizing the hen feed formulation, not only from an economic perspective, but also considering the environmental aspects involved. (C) 2018 Elsevier Ltd. All rights reserved.