A transmission electron microscopy study was carried out to examine the dislocation structure of normalized steel 09G2S that exhibits a strain aging effect. In a specimen stretched to the yield point, the maximum dislocation density is observed in the center (active zone) of the localized deformation band and decreases by about an order of magnitude at the band edges. The structure of these band regions, which are at different stages of strain hardening, is analyzed. The Burgers vector of dislocations of the primary slip system is determined; the dislocation ends form ordered flat dipole walls, leading to slip polygonization. The relationship between the specimen structure at the yield point and at the ultimate load is considered.