Water soluble polyzwitterions have been synthesized by free radical copolymerization of acrylamide with the novel carboxybetaine monomer, 2-(2-acrylamido-2-methylpropyldimethylammonio) ethanoate (AMPDAE). Feed ratios of 10 to lOOmol% AMPDAE were employed to give the polyzwitterion series, DAEAM. Copolymer compositions of low conversion samples were determined from i3C n.m.r. by integration of the carbonyl resonances. Reactivity ratios were determined yielding an rlr2 value of 0.6. Molecular weights range from 6.3 to 10.4 x lo6 gmol-' as determined by low angle laser light scattering. Dilute solution properties of the copolymers have been studied as a function of added electrolytes and pH. Intrinsic viscosity behaviour in NaCl solutions is dependent on the mol% of AMPDAE incorporated into the copolymers. Reduced viscosities were also examined as a function of the nature of added electrolytes, displaying higher viscosity values in accord with the Hoffmiester lyotropic series. The copolymers exhibit an enhancement in viscosity as pH is lowered due to protonation of the carboxylate groups which renders the polymer coil cationic due to the presence of quaternary ammonium groups. The solution behaviour of the copolymer containing 25 mol% AMPDAE, which possesses one methylene unit between the quaternary ammonium group and the carboxylate group, is compared to that of a copolymer containing 25 mol% 4-(2acrylamido-2-methylpropyldimethylammonio) butanoate, which possesses three methylene units between the charged centres.