Abstract. Ecotoxicology is a multidisciplinary research area investigating toxic effects of environmental pollutants and contaminants on biological populations, communities, and ecosystems. Wildlife toxicology studies can be traced to the original research efforts of the 19th and early 20th centuries. Researchers focused on well known cases of poisoning evidence of wildlife species, such as lead poisoning by birds and large poisoning of aquatic organisms from maritime petroleum oil spills. The increased use of fertilizers and pesticides in the 1930s and 1940s were investigated by toxicologists in wildlife birds of prey. The indentification in the 1960s of persistent organic pollutants (POPs) and other toxic substances in environmental samples, initiated a great range of ecotoxicological studies in wildlife birds and mammals. Polychlorinated compounds, heavy metals, new agrochemicals, pesticides, polycyclic aromatic hydrocarbons (PAHs), oil pollution, industrial and urban chemical waste, water pollution and other emerging pollutants (medicinal waste, cosmetics, chemicals with endocrine disrupting properties, microplastics and nanoplastics, polyfluorinated compounds) are some of the new and ongoing research subjects of ecotoxicological studies. These results were used to perform ecological risk assessment not only at individual biological species, but to community populations across multiple ecosystems. Biomonitoring of hazardous chemicals across trophic levels, development of new biomarkers, population modeling, etc., were major research issues developed in recent years. In this review we present some of the most prominent ecotoxicological studies on wildlife organisms and the ecological risk assessments of sensitive ecosystems on Earth that were published in specialized scientific publicationς.