The occurrence and fate of ten antibiotics were investigated in a municipal wastewater treatment plant in Southwest China. Antibiotics were identified and quantified using high performance liquid chromatography/tandem mass spectrometry after solid-phase extraction. The results showed that 10 antibiotics were present in wastewater, in concentrations ranging from ng L -1 to microg L-1. All of the target antibiotics were also detected in sludge with concentrations ranging from (0.92 +/-0.18) to (466.76 +/-77.46) ng.g-1, with azithromycin having the highest concentration (466.76 ng.g-1 dry weight). Mass balance analysis showed that biotransformation/ biodegradation was the main removal mechanism for the selected antibiotics, and sorption onto sludge was a relevant removal pathway for quinolone antibiotics, and azithromycin, which accounted for 9. 35% to 26. 96% of the initial loadings.