Duplicate (250g) samples of air dried sewage sludge / mixtures in different percentages were placed in sintered glass to conduct a study of the mobility of heavy metals in soil amended with sewage sludge. The pH values of saturation extracts showed an increase in all sample mixtures up to 3rd month. The concentrations of nickel in the extracts were higher than those of cadmium and lead. There was a marked depletion in levels of metals with time, thus showing that the greatest release of metals occurred in the early stages after mixing probably due to the flushing out of the initial soluble forms already present in sludge. Another possibility could be that the decrease in metal concentrations with time could be due to the development of anaerobiosis.