Furan is a chemical used in some industrial products and occurs naturally in heat-treated foods. We aimed to investigate the effects of orally administered furan on liver and kidney in growing Wistar male rats for 90 days. In this respect, biochemical, morphological, histopathological, and histomorphometrical examinations were performed. Three- to 4-week aged rats were divided into five groups of eight animals each; control, oil control; 2, 4, 8 mg/kg/day furan treatment groups. At the end of the experiment, antioxidant enzyme activities and serum AST, ALT, HDL, Urea, etc. levels were analyzed. Malondialdehyde (MDA) levels, superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-a (TNF-a), and interleukin-6 (IL-6) were also measured in liver homogenates. Also, liver and kidney were examined morphologically and histopathologically under light microscopy. According to the results of biochemical analysis, ALT, ALP, and LDL levels in treatment groups were significantly different compared with control groups. While LDL levels in treatment groups increased significantly, ALT and ALP levels decreased significantly. No significant changes were observed in liver MDA levels, superoxide dismutase and catalase activities in treatment groups. While IL-6 levels did not change in treatment groups, furan caused dose-dependent increases in liver TNF-a level of rats. In treatment groups, absolute and relative liver weights changed significantly, however, no significant changes were observed in kidney and relative kidney weights. Hyperemic blood vessels in the liver and congestion, edema, fibrosis, and tubular damage in the kidney of rats treated with furan were observed histopathologically. According to histomorphometric examinations, glomeruli diameters and glomerular volume decreased in the kidneys of rats in treatment groups. (c) 2011 Wiley Periodicals, Inc. Environ Toxicol, 2012.