Forty-eight BALB/C mice (30 males, 18 females) and 18 male Wistar rats were given Kargasok tea in their drinking water. Zero, 15, 25, 50, 75 or 100% concentrations were administered to mice for 2 or 8 w while the rats were given 0, 15 or 50% concentrations of the beverage for 12 w. Neither the mice nor rat's organ/body weight ratios were significantly affected by treatment. Rats receiving 15 or 50% concentrations of the tea had nephropathy and non-suppurative necrosis of the duodenum, pancreas and intestine. No significant microscopic lesions were found in any treated mice even when given 100% concentration of the tea. These findings suggest species variation in susceptibility to toxicity from the tea. The tea may be a cause of renal failure, diabetes mellitus and malabsorption syndrome and may not be safe for human or animal consumption.