Agaricus brasiliensis (=Agaricus blazei, Agaricus subrufescens) orSun mushroom has widespread use for potential health benefits such anti-tumor and immunomodulatory effects. Studies detected that others edible mushrooms affected renal metabolism and despite the widespread use of A. brasiliensis there are no studies that address biological effects on the renal function indices after their oral administration. Therefore, this study had as objective to verify the effects on kidney function indices after long intake of A. brasiliensis mycelium. Approach: Wheat grains was cultured during 18 days with Agaricus brasiliensis mycelium by solid state culture and used for chown formulation. Groups of female Swiss mice (20 per group) were fed during 14 weeks with 100 and 50% of the formulated feed denominated A100 and A50, respectively. Control group receivedformulated chown with wheat grains without mycelium. The water intake and excreted urine volume; the physic chemistry analysis of the urine and the serum levels of glucose, proteins, urea, creatinin and uric acid was determined (Meditron Junior-Boehringer, reagent strips Combur 10; microscopy and ADVIA 1650 Bayer). Results: A100 and A50 groups ingested 19.1 and 15.8% more water compared to C group, respectively. The urine and serum analysis showed that the verified parameters remained invariables for all groups, including glucose levels, which resulted in a 10% reduction of A100 group, without statistical difference (p>0.05 Vs C). Conclusion/Recommendations: The prolonged intake of supplemented feed with A. brasiliensis mycelium didn’t result in indicative alterations in the kidney function indices. The preventive use of the mushroom did not show any deleterious effects on kidney; however complementary studies are necessary to guarantee complete safety; possible correlation between increase of urinary excretion and hypotensive effect reported in the literature and also studies with diabetics animals to verify an possible hypoglycemic effect of the A. brasiliensis mycelium.