Microcystins (MCs) are a group of biologically active monocyclic hepatopancreatic peptides produced by some bloom-forming cyanobacteria in water. Toxic cyanobacterial blooms act as hepatotoxic, neurotoxic, cytotoxic in human and animal following long term ingestion of contaminated water. Plants, vegetables and food crops irrigated with microcystins contaminated water are negatively affected by MCs. Temperature light and high concentrations of nitrogen and phosphorus exposure are the primary three environmental factors that promote the formation of cyanobacterial blooms in surface water. MCs have been accumulated in plants, various aquatic organisms and animals until reach the top food chain. Therefore, high level of toxic cyanobacterial blooms in surface water has become an increasing environmental problem all over the world. Many countries in the world suffer from the problem of intensive cyanobacterial blooms in surface water. Hence the necessity for regular monitoring of the organic wastes discharge to the surface water should be highlighted and educating people about the dangers of microcystins on water hygiene standards as well as on aquatic, animal and human life.