The purpose of this paper is to present an integrated life cycle assessment of the electricity grid of Greece, considering the different power generation technologies currently operating in the country and the interconnected electricity transmission system. The energy and environmental assessment of both the generation and transmission systems is carried out employing SimaPro 7.1 Life Cycle Assessment software. The present work shows that the main, environmentally adverse, impacts (>60%) are associated with the electricity generation sector; in particular, with the system of mainland Greece, which is dominated by centralized fossil-fuelled power plants. Transmission of electricity was found to have 70% -90% lower life cycle impacts compared to generation. Transmission power losses are the most important contributor to GHG emissions, whereas transmission lines infrastructure and transformers are associated with much lower life cycle impacts. Findings concerning the primary energy demand exhibit analogous behaviour. Future electricity supply mixes with high shares of renewables could lead to substantially lower GHG emissions, whilst primary energy demand is expected to increase, due to the electricity intensive construction stage of renewables. Results concerning the contribution of electricity generation and transmission to environmental impacts related to human toxicity, ecosystem quality, resources depletion, etc., are also reported and discussed. (C) 2019 Elsevier Ltd. All rights reserved.