Aq. N-vinylformamide was copolymerized radically with acrylic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, and maleic acid. The resulting copolymers were hydrolyzed to yield amphoteric polyelectrolytes. These were modified to yield practicable [products like polymeric surfactants, ampholytes with zwitterions, and xathogene derivatives. A polyampholyte carrying sulfonic groups and its protonated form (M = 1.17.10(6)) proved particularly useful for making drilling muds. Potentiometric titration curves for aqueous polyampholytes, reduced viscosity, and C-13 NMR spectra were determined.