The homopolymer of maleic anhydride was synthesized by free radical initiation and characterized. Molecular mass measurements of 14 selected fractions yielded M(w) ranging from 1.1 x 10(4) to 14.7 x 10(4) g/mol. Intrinsic viscosities obtained from the fractions in DMF at 25 degrees C were analyzed on the basis of the theory of Yamakawa et al. The persistence length was 2.3 +/- 0.1 nm and M(L) was 600 +/- 10 nm(-1). The conformation of the poly(maleic anhydride) molecules in DMF is considered to be semiflexible.