The Guidelines include systematic reviews of the scientific evidence of the critical health effects of environmental noise: effects on sleep, annoyance, cognitive impairment, cardiovascular diseases, hearing impairment and tinnitus. Other potential health outcomes with less evidence are also systematically reviewed, but have less impact on the development of recommendations: adverse birth outcomes, quality of life, mental health and wellbeing, and diabetes and metabolic diseases. The noise sources considered include aircraft, rail, road, wind turbines and leisure noise. Additionally, the Guidelines review the potential health benefits from noise mitigation and interventions to decrease noise levels. The systematic reviews conducted for the Guidelines have revealed some key knowledge gaps and research needs, which will need to be filled in the future in order to provide stronger advice for the protection of the population from the harmful effects of noise. These gaps are related to the combined health effects of different noise sources and other environmental exposures, the lack of harmonization in the methods and metrics used to measure health outcomes and noise exposure, the paucity of longitudinal studies, and other issues related to the assessment of effectiveness of interventions for the reduction of noise exposure and improvement of health outcomes. © 2016, German Acoustical Society (DEGA). All rights reserved.