To examine the distribution and status of Cu, Cr, Pb, Zn, Cd, and Ni in the mud of Tsurumi River, surface mud samples were collected at 8 stations from the mouth to up the river. Total heavy metals of mud in the upper and middle part of the river showed values near the mean of heavy metals in Japanese rivers of the first category. Ethylenediaminetetraacetic acid (EDTA)-soluble Cu represented 30% of the total Cu, while Cd, Pb, and Zn 10 to 20% and Cr, Ni about 5%. Acid-soluble heavy metals were 10% higher than EDTA-soluble heavy metals. In the mouth of the river, near the Tsurumi industrial area, the total heavy metals were 2 to 6 times more than that in the upper and middle of the river. EDTA-soluble Cu and Cd showed about 60% of the total Cu and Cd, Zn and Pb about 70% and Cr and Ni 10 to 20%. Acid-soluble heavy metals were 10 to 20% more than that of EDTA-soluble metals. Therefore 1/2 to 2/3 of total heavy metals were extracted with 0.5 N HCl. These data indicated that a large portion of heavy metals in the mouth of the river came from industrial wastes and that such heavy metals can be extracted with 0.5 N HCl or EDTA.