Epidermal growth factor (EGF) is a small mitogenic protein. Proteins with sequence homology with EGF or with its membrane-bound protein receptor have been proposed to play a role in oncogenesis. This report describes solution NMR data that provide evidence that the solution conformation of murine EGF includes an anti-parallel beta-sheet structure involving residues S2-P4, V19-I23, and S28-N32; a small anti-parallel beta-sheet involving residues Y37-S38 and T44-R45; and a multiple-bend (or short irregular helix) structure for residues C6-C14 that is disulfide bonded to the V19-I23/S28-N32 beta-sheet. Implications of these results for structure and function studies of EGF and for molecular design of EGF and homologous alpha-type transforming growth factors are discussed.