The proton magnetic resonance of aqueous N-methylacetamide solutions has been studied as a function of the mole fraction of water and as a function of temperature. Shifts to lower applied fields with a decrease in temperature were observed for both the water and N—H proton resonances. An increase in water concentration was found to produce a high field shift in the N—H proton resonance indicative of a net hydrogen-bond structure breaking effect. The water proton resonance, however, was found to undergo a periodic shift with respect to water concentration. The NCH3 and CCH3 proton resonances were not significantly affected by temperature or concentration changes. © 1968, Walter de Gruyter. All rights reserved.