A method of purifying a recombinant human N-acetylgalactosamine-6-sulfatase (GALNS) enzyme, said GALNS enzyme comprising an amino acid sequence at least 95% identical to amino acids 27 to 522 of SEQ ID NO:4, wherein said GALNS enzyme: has a purity of at least 95% as determined by Coomassie Blue staining when subjected to SDS-PAGE under non-reducing conditions, has at least 50% conversion of the cysteine residue at position 53 to C α -formylglycine (FGly), and has between 0.5 to 0.8 bis-phosphorylated oligomannose chains per monomeric protein chain, and wherein at least 98% of said GALNS enzyme is in the precursor form as determined by sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE), comprising: a) filtering a culture medium containing the GALNS enzyme secreted from a mammalian cell line that expresses human sulfatase modifying factor 1 (SUMF1) and the recombinant human GALNS enzyme, ultrafiltering/diafiltering the filtered culture medium, whereby the ultrafiltered/diafiltered culture medium is concentrated about 20X, and charcoal filtering the 20 X concentrated ultrafiltered/diafiltered culture medium; b) loading the charcoal filtered 20X ultrafiltered/dialfiltered culture medium from step a) onto a Zn-chelating Sepharaose FF capture column, washing the column under conditions such that the GALNS enzyme is retained on the column, and eluting the GALNS enzyme from the column; c) filtering the eluate from the Zn-chelating Sepharaose FF capture column in step b) through a filter to remove viruses; d) adjusting the pH of the eluate from the Zn-chelating Sepharose FF capture column filtrate from step c) to about pH 4.5 ± 0.1, and filtering the pH 4.5-adjusted eluate from the Zn-chelating Sepharose FF capture column filtrate; e) loading the pH 4.5-adjusted filtrate from the Zn-chelating FF capture column from step d) onto a Fractogel EMD SE Hi-Cap cation exchange column, washing the column under conditions such that the GALNS enzyme is retained on the column, and eluting the GALNS enzyme from the column; f) adjusting the pH of the eluate from the Fractogel EMD SE Hi-Cap cation exchange column from step e) to about pH 3.5 ± 0.1 for viral inactivation; g) adjusting the pH 3.5-viral inactivated eluate from step f) to about pH 5.0, then loading the pH 5.0-adjusted viral inactivated eluate onto a ToyoPearl Butyl 650 M polishing column, washing the column under conditions such that the GALNS enzyme is retained on the column, and eluting the GALNS enzyme from the column; h) buffer exchanging the eluate from the ToyoPearl Butyl 650 M polishing column from step g) into a formulation comprising 20 mM NaOAc/HOAc, 50 mM NaH 2 PO 4, 30 mM arginine HCl, 2% (w/v) sorbitol, pH 5.4, and adjusting the concentration of the GALNS enzyme in the formulation to about 3 mg/mL; i) removing any residual virus and/or DNA by filtering the buffer exchanged formulation in step h) with a DV20 filter and a Mustang Q filter; and j) adding polysorbate 20 to the formulation in step i) to a final concentration of 0.01% (w/v). has a purity of at least 95% as determined by Coomassie Blue staining when subjected to SDS-PAGE under non-reducing conditions, has at least 50% conversion of the cysteine residue at position 53 to C α -formylglycine (FGly), and has between 0.5 to 0.8 bis-phosphorylated oligomannose chains per monomeric protein chain, a) filtering a culture medium containing the GALNS enzyme secreted from a mammalian cell line that expresses human sulfatase modifying factor 1 (SUMF1) and the recombinant human GALNS enzyme, ultrafiltering/diafiltering the filtered culture medium, whereby the ultrafiltered/diafiltered culture medium is concentrated about 20X, and charcoal filtering the 20 X concentrated ultrafiltered/diafiltered culture medium; b) loading the charcoal filtered 20X ultrafiltered/dialfiltered culture medium from step a) onto a Zn-chelating Sepharaose FF capture column, washing the column under conditions such that the GALNS enzyme is retained on the column, and eluting the GALNS enzyme from the column; c) filtering the eluate from the Zn-chelating Sepharaose FF capture column in step b) through a filter to remove viruses; d) adjusting the pH of the eluate from the Zn-chelating Sepharose FF capture column filtrate from step c) to about pH 4.5 ± 0.1, and filtering the pH 4.5-adjusted eluate from the Zn-chelating Sepharose FF capture column filtrate; e) loading the pH 4.5-adjusted filtrate from the Zn-chelating FF capture column from step d) onto a Fractogel EMD SE Hi-Cap cation exchange column, washing the column under conditions such that the GALNS enzyme is retained on the column, and eluting the GALNS enzyme from the column; f) adjusting the pH of the eluate from the Fractogel EMD SE Hi-Cap cation exchange column from step e) to about pH 3.5 ± 0.1 for viral inactivation; g) adjusting the pH 3.5-viral inactivated eluate from step f) to about pH 5.0, then loading the pH 5.0-adjusted viral inactivated eluate onto a ToyoPearl Butyl 650 M polishing column, washing the column under conditions such that the GALNS enzyme is retained on the column, and eluting the GALNS enzyme from the column; h) buffer exchanging the eluate from the ToyoPearl Butyl 650 M polishing column from step g) into a formulation comprising 20 mM NaOAc/HOAc, 50 mM NaH 2 PO 4, 30 mM arginine HCl, 2% (w/v) sorbitol, pH 5.4, and adjusting the concentration of the GALNS enzyme in the formulation to about 3 mg/mL; i) removing any residual virus and/or DNA by filtering the buffer exchanged formulation in step h) with a DV20 filter and a Mustang Q filter; and j) adding polysorbate 20 to the formulation in step i) to a final concentration of 0.01% (w/v).