Background: The constant input of antibiotics into the urban sewage system may lead to accumulations in sewage biosolids (sediment, sewage sludge). A possible input into the environment might be associated with an increasing risk for (multi-)resistance bacteria. Objectives: The present study shows which of the most prescribed antibiotics accumulate in the urban sewage system. Material and methods: Antibiotics in urban sewage sediment and sludge were analyzed by ultrasonic (USE) and solid-phase extraction (SPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results: In urban sewage sediment, 9 of the 16 selected compounds were determined with concentrations up to 803 μg/kg dry weight for ciprofloxacin. In sewage sludge, 7 and 5 antibiotics were quantified in primary and digested sludge, respectively. High stability with an accumulation in all investigated sewage biosolids were found for cipro- and levofloxacin, doxycycline as well as azi- and roxithromycin. Conclusions: The spectrum of sorbed antibiotics decreased during sewage sludge treatment. In digested sludge, only 5 of the 16 selected antibiotics were determined. Their possible environmental impact caused by high retention time in the sewage system might be associated with (multi-)resistant bacteria and has to be considered in further investigations.