The aim of the present study was to examine the content, and its change with time, of 4-nonylphenol and nonylphenol ethoxylates in sewage sludge from Polish municipal wastewater treatment plants. The sludge samples from twelve wastewater treatment plants were examined for three consecutive years (2005-2007). The content of 4-NP was determined only in one set of samples from 2005 and in those from 2007. In none of them it exceeded 1 mg/kg. The content of NPEOs in the samples examined decreased with time, from more than 200 mg/kg in 2005 to 10-30 mg/kg at the end of the study; in most of the samples it proved to be below 50 mg/kg - the new threshold value proposed by the EU.