Cyanobacterial blooms are a potential health hazard due to the ability of some species to produce toxins that are harmful to other living organisms. This review provides a comprehensive summary of anecdotal and case reports on acute poisonings in animals and humans attributable to cyanotoxin exposure in fresh- and brackish-waters. Approximately two-thirds of reported poisonings have occurred in Europe and the United States. Dogs and livestock account for the majority of reported cases involving animal exposure to cyanotoxins, while recreational activities are responsible for approximately half of reported incidents involving human exposure. Due to data limitations it is difficult to estimate the total number of animals and humans affected by cyanotoxins, however, some general observations regarding frequency and numbers affected are made. The review demonstrates that cyanotoxins have, and will likely to continue to have, potentially serious consequences for public health and animal welfare worldwide.