Objective: to determine the acute toxicity of the alcoholic and hydroalcoholic extract of leaves and stem of Senna occidentalis in nauplii of Artemia franciscana. Methodology: The Artemia eggs were acquired at the Fishmen Aquarium, located in the city of Iquitos, Department of Loreto. These eggs went through a hatching process until they became nauplii. A. franciscana eggs were incubated in a 3% Instant Ocean solution for 48 to 72 hours. For convenience, organs were collected from the study species and used to prepare both extracts from the micropulverized plant sample; The sample was macerated with ethanol, ethanol:water, then filtered, concentrated in rotary steam and subsequent physical elimination of the solvent, being tested at 10, 100 and 1000 ppm on A. franciscana nauplii. Results: The LC50 of the two extracts studied (alcoholic and hydroalcoholic) were higher than 1000 ppm. Concl...