Determining total heavy metal content in sewage sludges and composts produced of waste substances does not allow for an assessment of the bioavailability of those elements. Therefore the investigations were conducted to determine the concentrations of mobile heavy metal forms in such materials. Total heavy metal content in the analysed sewage sludges and compost made of green wastes grade I does not exclude their agricultural use. Exceeding the permissible concentrations of lead and cadmium in the compost made of municipal wastes grade II and high content of glass and ceramics make biological utilization of this material impossible. Heavy metal concentrations in individual fractions extracted from the analysed sewage sludges and composts were highly diversified depending on the investigated metal and kind of analysed organic material. The obtained results show that heavy metals in the studied organic materials occur generally in the form of more hardly available compounds.