In the present study a toxicity evaluation (Heterocypris incongruens, OstracodToxKit FTM Test) was carried out for ten municipal sewage sludges in relation to polycyclic aromatic hydrocarbon (PAH) contents in these sludges. PAHs content in the sewage sludges was determined by a vigorous extraction method and solid phase extraction with Tenax-TA. The main aim of the evaluation was establishing whether it was possible to determine the negative influence of PAHs in the sewage sludges on H. incongruens mortality and growth inhibition using the Tenax-TA method. H. inconguens showed increased growth inhibition and mortality when exposed to all sewage sludges. Significant relationships were noted between the content of some Tenax-TA PAH fractions and the total organic carbon content, cation exchange capacity and concentration of Ca(2+) ions. The toxicity was proportional to Tenax-TA concentrations and was not governed by the total concentration found in the sewage sludge.