Ivermectin and abamectin, members of the avermectin family of compounds, were introduced to the market in the 1980's as a veterinary antiparasitic drug and agricultural pesticide, respectively. Their acceptance and commercial success have been remarkable; both are highly effective and in worldwide use. The efficacy of ivermectin in river blindness has expanded the interest in its use in human medicine. In response to the intense scientific and industrial interest in ivermectin and abamectin and the likelihood that they will be forerunners of an expanding family of drugs, this comprehensive monograph satisfies the need for a review and synthesis of current knowledge about the use of these substances in crop protection as well as in cattle, sheep, swine, horses, dogs, cats, birds, fish, reptiles, and in man. This overview presents chemical, biochemical, and microbiological data, as well as pharmacological, safety, and environmental aspects and covers practical use of the compounds as antiparasitic and pesticide agents, as well as the available safety data that have emerged from the clinical experience with human applications.