MONITORING changes of the main chemical properties ofsewage sludge from Sirt Wastewater Treatment Plant, Libya wasinvestigated. Ten random sewage sludge samples were monthlycollected for a time span of one year. Average year values of TDS, pH,organic matter and C/N recorded 1428.91 mg kg-1, 6.90, 76.3% and7.97, respectively. Total N, P and K contents were in the normal range(5.63, 1.41 and0.019%, respectively). The total concentrations of Fe,Zn and Mn recorded high levels (2768, 1142 and 169 mg kg-1,respectively). Low and more fluctuated total concentrations of Cu, Pband Ni were recorded (107, 45 and 35 mg kg-1, respectively). Ingeneral, the total concentrations of heavy metals were found to be farbelow the US-EPA ceiling limits except Cd and As which hadconcentrations at or very close to their ceiling limits. The BCRsequential extraction scheme was applied to investigate thefractionation of heavy metals in the sludge. More than 50% of total As,Pb, Fe, Mn and P were found in the fourth residual stable fractionwhile the other heavy metals were mostly released in the first threemore mobile fractions (soluble-exchangeable, reduceable andoxidizable) of the applied fractionation scheme. Special cautionsshould be considered when using this sludge safely in agricultureconcerning the calculation of the loadings of heavy metals and theirmobility in soils.