Particularly in view of the pharmacological use of PVP it seemed interest- ing to study the stability of the amide bond of PVP and low molecular weight analogues in aqueous solutions and the extent to which it can be hy- drolyzed at different hydrogen ion concentrations. It also was of interest to determine whether or not it would be possible to prepare a polyampholyte by complete hydrolysis of PVP. In order to provide this information the lactam-amino acid equilibrium at 100°C. was studied over the entire pH range for PVP as well as for the low molecular weight analogue, N-ethyl- pyrrdidone (EP) .