The use of multiple quantum filters for simplification and editing of one-dimensional 1H NMR spectra of proteins is demonstrated. Three, four and five quantum-filtered spectra have been recorded. The technique is applicable to proteins of molecular weight up to at least 18,000. Examples obtained for a mixture of amino acids and for the proteins plastocyanin and myoglobin are reported. A remarkable degree of spectral editing can be achieved by judicious choice of experimental parameters.