The magnetic domain structure of polycrystalline grain‐oriented 3¼% silicon steel has been investigated by the magnetic‐powder‐pattern technique and the orientation of individual grains determined by the etchpit optical‐goniometer technique. A semiquantitative relationship has been found between the domain patterns and crystalline orientation. The observed powder patterns can be grouped into five types, depending upon the angle, &phgr;, between the rolling plane and the <100> direction lying closest to the rolling plane. When the rolling direction is known and &phgr; is <10°, semiquantitative grain‐by‐grain orientation information can be obtained solely from the domain patterns.The behavior of two of the types of patterns in an applied magnetic field is shown, and on the basis of this behavior, a three‐dimensional domain configuration is proposed for one of the less complicated surface patterns.