Fucoidan is a polysaccharide with high viscosity and mucilage, which contains significant proportion of sulphate ester group and L-fucose. It is present in intercellular spaces of brown algae. This study aimed to investigate the effect of fucoidan on some biochemical parameters and kidney tissues in nephrotoxicity induced by GM in rats. The rats used in the study were randomly divided into 4 groups. Each group had 7 rats as control, fucoidan, GM and GM+fucoidan. Blood samples were taken after 24 hours from the end of experiment which lasted eight days. Creatinine, BUN, uric acid, glucose, triglycerides, total cholesterol, VLDL, HDL, total bilirubin levels and ALT, AST, ALP, LDH, CK, amylase activities were assayed by an autoanalyser. The kidney tissues were examined histopathologically. In GM+fucoidan group, creatinine (p<0.001), BUN (p<0.001), uric acid (p<0.05), triglycerides (p<0.05), VLDL (p<0.05), AST (p<0.001), ALP (p<0.05), LDH (p<0.001), CK (p<0.01) levels statistically decreased, however HDL (p<0.05) level increased when compared to GM group. As conclusion, it can be said that administering fucoidan during GM toxicity decreases the nephrotoxicity damage. Considering biochemical parameters and histopathological findings, fucoidan can be suggested as a protective agent for kidneys in nephrotoxicity induced rats.