In biochemistry, sulfatases EC 3.1.6.- are a class of enzymes of the esterase class that catalyze the hydrolysis of sulfate esters into an alcohol and a bisulfate: These may be found on a range of substrates, including steroids, carbohydrates and proteins.

Together with sulfotransferases, sulfatases form the major catalytic machinery for the synthesis and breakage of sulfate esters.

Steroid sulfatase is distributed in a wide range of tissues throughout the body, enabling sulfated steroids synthesized in the adrenals and gonads to be desulfated following distribution through the circulation system.

Many sulfatases are localized in the lysosome, an acidic digestive organelle found within the cell.

Genetic defects in sulfatase activity can arise through mutations in individual sulfatases and result in certain lysosomal storage disorders with a spectrum of phenotypes ranging from defects in physical and intellectual development.