► Analysis of emerging contaminants, seven parabens and two by-products, in sludge. ► Paraben levels in sewage sludge from 19 WWTPs located in the region of Madrid. ► Methylparaben and propylparaben were the main parabens detected in sludge. ► Occurrence and time-course of parabens in samples from WWTPs during four years. A rapid method for determination of seven parabens and two chlorinated by-products in sewage sludge was developed based on matrix solid-phase dispersion and gas chromatography–tandem mass spectrometry. The analytical procedure showed good recoveries that ranged from 80 to 125%, with relative standard deviations lower than 12% and low detection limits, ranging from 0.1 to 2.0ngg−1 dry weight. The developed method was applied to the analysis of sewage sludge collected during 2010 in 19 wastewater treatment plants (WWTPs) located in various urban, industrial or rural zones in Madrid (Spain). Methylparaben was found in most of the WWTPs sampled (95%) at levels between 5.1 and 26.2ngg−1 dry weight and propylparaben was detected in 74% of the WWTPs at levels up to 44.1ngg−1 dry weight. In order to study the temporal variation of parabens and two chlorinated parabens during a four-year period, sludge samples were collected from 3 selected WWTPs. The levels of methylparaben encountered were rather constant throughout the sampling period whereas propylparaben levels slightly increased. In one of the WWTPs monitored, isopropylparaben was found at the beginning of the sampling period but its content decreased and was not detected in the 2010 sampling.