Results on the metal-free anionic polymn. of Bu acrylate (BA) are presented. BA was polymd. in THF, using tetrabutylammonium 2-nitropropanate as initiator. With very pure initiator, the polymn. started without inhibition periods, which may be caused by transfer reactions between the precursor mol. 2-nitropropane in the synthesis of the initiator and growing chains. Even the addn. of 2-nitropropane or of di-Et 2-ethylmalonate, the precursor of the initiator tetrabutylammonium di-Et 2-ethylmalonate, did not cause significant inhibition periods, which are obsd. in the corresponding polymn. of Me methacrylate. Under our reaction conditions, curves from dilatometric measurements showed no marked induction periods, usually attributed to an initiation reaction which is slower than the propagation reaction. The overall polymns. of BA did not usually go to complete consumption of the monomer. The well-known intramol. cyclization reaction was detd. as the major termination reaction.