Four groups of about 25 mice were fed 0%, 0.02%, 0.2% or 2% sodium saccharin (w/v) in their drinking water for up to 100 days. Two groups of 10 mice were injected with 0.2 ml or 4% or 8% sodium saccharin (w/v) interperitoneally. One group of 10 mice was given 0.2 ml of 8% sodium saccharin (w/v) subcutaneously. One group of 5 mice was given 0.2 ml of saturated saccharin subcutaneously. These groups were controlled with the administration of sterile normal saline in the corresponding amounts and manner. Significant enlargement of kidneys, hard-ened and reddened bladders and enlarged, distended, reddened uteri were observed.