A complex study of the properties of poly-N-vinylsuccinimides synthesized by the reversible addition-fragmentation chain transfer polymerization (RAFT) was carried out by the methods of molecular hydrodynamics. Molecular masses were determined from the sedimentation-diffusion analysis, the range was 5000 < M, g/mol < 68000. Scaling relationships of hydrodynamic characteristics with molecular mass were established, and the conformational characteristics of molecular chains of poly-N-vinylsuccinimides were estimated. The value of the statistical segment, determined from the data on translational and rotational friction, was (2.7 ± 0.1) nm. The polydispersity of several samples was evaluated from the results on velocity sedimentation.