Karwinskia humboldtiana (Kh) is a poisonous shrub causing a number a accidental intoxications in humans. In previous studies, damage has been reported to Peripheral and Central Nervous System. Main intoxication sign is the presence of paralysis. However, no studies have been documented about damage to other organs like the kidney. The objective of this research is to evaluate kidney histology during chronic intoxication. Thirty two (32) Wistar rats were divided into 4 groups (n=8). For each group, 5 rats were intoxicated with Kh and 3 received water only as a control. Intoxicated rats received 3.5 g/Kg body weight of dry powder of Kh fruit, fractionated in 5 doses as follows 1.5, 0.5, 0.5, 0.5, 05 on days 0, 3, 7, 10 and 14 respectively. Control rats received water only. Each group was euthanized at different times during paralysis evolution. Samples of kidney were obtained and processed by routine technique until paraffin embedding for light microscopy studies, and in epoxy resins for transmission electron microscopy. Sections were obtained and stained with H&E, Masson's trichrome, and treated for PAS with diastase reaction to demonstrate basal membranes. At the light microscopic level we observed blood vessel congestion, tubular necrosis and fibrosis of renal capsule. Both at Light microscopy and electron microscopy, it was identified a thickening of the filtration barrier and of renal capsule, in all intoxicated animals, especially in the recovery group. These findings demonstrate that Kh causes a systemic intoxication and not only of the nervous system, as has been considered up to now.