One of the most challenging tasks facing those who work with low-spin ferriheme proteins is assigning all of the heme proton NMR resonances. In part this stems from the relatively large resonance line widths and rapid relaxation rates characteristic of hyperfine-shifted protons. Perhaps as important is that, depending upon the protein, approximately one-half of the hyperfine-shifted resonances are buried in a very dense spectral region. Identifying single hyperfine-shifted proton resonances in an extremely crowded spectrum imbues the resulting assignments with a degree of uncertainty. In an attempt to simplify this procedure, we have produced an extensively deuterated Component IV globin of Glycera dibranchiata in an expression system consisting of the E.; coil strain BL21 (DE3) grown in a medium that was at least 98% deuterated. After purification, this globin was constituted with fully protonated hemin to form the recombinant deuterated monomer hemoglobin, which was subsequently studied by both 1D and 2D NMR methods. Complete deuteration makes comprehensive heme proton assignments rapid to achieve, straightforward, and unambiguous. All heme proton resonances are identifiable in partially relaxed 1D spectra, including those of the heme meso protons. Moreover, our experience with this completely deuterated protein offers insights to many general and potential uses of completely deuterated proteins.