This study uses life cycle assessment to evaluate the environmental impacts of electricity generated from fossil fuels in Chile over a ten–year period, from 2004-2014. The focus on fossil fuels is highly relevant for Chile because around 60% of electricity currently comes from natural gas, coal and oil. The impacts are first considered at the level of individual technologies, followed by the evaluation of the fossil-fuel electricity mix over the period. The study has been carried out using detailed primary data for 94 operating plants. Considering individual technologies, coal power has the worst performance for eight out of 11 impacts, with eutrophication, freshwater and marine ecotoxicity being between ten and 240 times greater than for gas. However, oil is worse than coal for photochemical oxidants (31%) and depletion of elements and ozone layer (four and eight times, respectively). Between 2004 and 2014, the annual environmental impacts doubled, while electricity generation rose only by 55%. The only exception to this is ozone depletion which fell by around 4%. The highest impacts occurred in 2014 mainly because of the high contribution of coal power. Therefore, the environmental performance of fossil-based electricity in Chile has worsened over time due to the growing share of coal power, coupled with the increasing electricity demand. Consequently, policy should aim to increase the efficiency of power plants, avoid the use of petroleum coke, improve emissions control and replace coal and oil with gas power as soon as possible.