Amphiphilc polybutadiene-b-poly(ethylenewdde) (PBPEO) blockcopolymers with two different ratios of blocklengths were synthezised by anionic polymerisation. The properties of the PBPEO micelles in aqueous solution were investigated by static light scattering and small-angle neutron scattering. Surprisingly the micellar shape of PBPEO aggregates differs grossly from that of the corresponding poly(ethylene-propylene)-b-poly(etyleneoxide) PEPPEO micelles.