The objective of the present work was to evaluate the toxicity of the aqueous extract of leaves of Tessaria integrifolia R. et. P. on organs of Rattus novergicus var. albinus, using the oral toxicity model at repeated doses for 28 days (toxicity test 407 of the guidelines of the Organization for Economic Cooperation and Development - OECD). 20 specimens Rattus novergicus var. albinus in 2 experimental groups of 10 specimens each (5 of each sex). Control Group: Physiological saline solution (0.9% SSF) was administered. Problem group: The leaf extract of Tessaria integrifolia R. et. P. at a dose of 500 mg/kg/day orally, administration was performed at 8:00 a.m. during the 28 days that the specimens received the treatments. At the end of the experience, euthanasia was performed with sodium pentobarbital 200 mg/kg intraperitoneally from the specimens and the organs were extracted, which were...