There is limited information on the toxicity of landfill leachate on somatic tissues and organs of mammals. The hepatotoxic and nephrotoxic effects of leachates from Olusosun and Aba-Eku landfills in Southwestern Nigeria in Wistar albino rats were investigated. Rats orally exposed to 1 – 25 % concentrations of each of the test leachates were examined for clinical signs of toxicity and body weight gain during exposure. Blood, liver and kidney of surviving rats were examined for serum biochemical parameters, organ weight gain and histopathology. Clinical toxicity signs include ungroomed hair, re-duced activities, hair loss, laboured breathing, reduced feed and fluid consumption, abscess and muscular disorder. There was concentration dependent sex related significant (p<0.05) decrease in body weight and increase absolute and relative liver and kidney weight gain. The test samples caused increase in aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine but decrease albumin and total proteins. These parameters showed sexual dimorphisms. Histopathological lesions in the liver and kidney include mild to severe multifocal degeneration of the hepatocytes, multiple periportal foci, cellular infiltration, interstitial haemorrhage cortical congestion, degenerative epithelia of renal tubules and necrosis. The concentration of heavy metals and anions in the test samples were above standard permissible limits. These findings show the potentials of landfill leachate to induce liver and kidney dysfunction in rat probably via free radical formation and/or direct chemical disruption of the organs. This may be of health risk in animal and human population expose to chemical substances from waste landfills.