Waste sludge from Zn manufg. was studied for content of Zn, Pb, Fe, Cd, Cu, Cr, Mn, As, Ni and TI and leached with NaOH soln. to recover mainly Pb and As, and then with a 25% NH3 conc. to recover mainly Zn and Cu but also Cd, Cr and Ni. After the teachings, the sludge still had the original contents of Fe, Mn, and TI. The highest removal degrees were achieved for Ni (100%), Cu (98%), Zn (97%) and As (96%). After the leaching, the sludge was no more toxic and hazardous waste.