MICROCYSTIS aeruginosa is a kind of cyanobacteria microorganism that synthesizes and produces peptides, which could be highly toxic. The most common toxin known as microcystin (MCs) or cyanotoxins, these toxins are heptapeptides produced by cyanobacterial blooms on water surfaces. They potentially lead to acute to chronic health-related problems via increasing reactive oxygen species (ROS) and irreversible inhibition of serine/threonine protein phosphatases. The toxicological studies of MCs on experimental animal and cell models have promise interests; however, few information is known about their impacts on humans due to acute or chronic exposure. This review article aimed to present some of the information about the cyanotoxins structure, occurrence, and distribution of the cyanobacterial toxins especially excreted from M. aeruginosa. Also, toxicological studies and investigations associated with M. aeruginosa producing microcystin, their assessments and control and health problems and cancer risk upon MCs exposure will be discussed. The article will also discuss the mechanism of the toxin and the way for control and degradation.