Absorption of elemental sulfur in rat was investigated. The purified sulfur (powder) containing radioactive crystalline rhombic elemental sulfur(S-35) was administered orally and found that considerable amounts of radioactivities were recovered from liver, jejunum, testis, and cartilage and also from blood, suggesting that elemental sulfur was absorbed in the animal body. It was also found that the radioactivity of sulfate in the blood, liver and cartilage was significantly high, indicating that the elemental sulfur was oxidized to sulfate. Analysis of acid mucopolysaccharides showed that a significant portion of the sulfate was incorporated into mucopolysaccharide sulfate in both liver and cartilage. From the above results, it is likely that absorbed elemental sulfur was converted to sulfate, which might be then incorporated into acid mucopolysaccharides.