The enhancement of sewage sludge to decrease its toxic effects on living organisms due to the high content of heavy metals (Cd, Cr, Ni and Pb) was studied using some organic and inorganic materials. Four materials (Silica gel, Cement Bypass, Rock phosphate and Charcoal activated carbon) were mixed with the sewage sludge in three rates (5, 15 and 25%) and the mixture of each two materials at a rate of 15% of each. Results indicated that DTPA extractable Cd, Ni and Pb decreased from 0.895, 12.097 and 26.02 ppm in the control to 0.376, 3.13 and 9.06 ppm, respectively (58, 74 and 65% reduction , respectively, compared with the control) with 25% of rock phosphate (RP). The lowest extracted Cr was obtained by the application of 25% silica gel with a reduction of 67% compared with the control. The maximum reduction in extracted Cd, Cr and Pb were resulted by the mixture of charcoal+ silica gel (0.33 ppm Cd), rock phosphate+ Silica gel and cement By-pass+Silica gel (0.04 ppm Cr) and rock phosphate+cement By-pass (9.98 ppm Pb), respectively. While, the mixture of silica gel with any other amendment under discussion always resulted in 100% reduction of extracted Ni.