Objective: This work aimed at assessing acute toxicity in Artemia salina of waters treated with natural coagulants (Moringa Oleifera) and with synthetic coagulants (Aluminum Sulfate Type B). Methods/Analysis: Acute toxicity tests were carried out on Artemia salina larvae to solutions with the highest coagulant activity by means of standard eco toxicology techniques and procedures. In addition, adjustments of sigmoid curve models were made to estimate mean lethal concentration (LC50) in this organism. Findings: Results obtained showed that the natural coagulant has low toxicity, making it a friendly alternative to replace aluminum sulphate, in water treatment. Application/Improvements: Moringa oleifera can have advantages over aluminum sulphate due to biodegradability. This is an efficient and non-toxic coagulant that can be used in water treatment for domestic use in urban and rural areas. Keywords: Acute Toxicity, Coagulant Activity, Artemia salina, Moringa oleifera, Innocuousness.