The present invention provides a highly purified recombinant human precursor N-acetylgalactosamine-4-sulfatase and biologically active mutants, fragments and analogs thereof as well as pharmaceutical formulations comprising highly purified recombinant human precursor N-acetylgalactosamine-4-sulfatase. The invention also provides methods for treating diseases caused all or in part by deficiencies in human N-acetylgalactosamine-4-sulfatase including MPS VI and methods for producing and purifying the recombinant precursor enzyme to a highly purified form.