We examined high‐resolution diffraction profiles of as‐grown and annealed magnetic‐field‐applied Czochralski (MCZ) silicon crystals which were about 300 &mgr;m thick and [001] oriented, and compared these profiles with the ultraplane wave x‐ray topographs. Rocking curves for the symmetric 220 diffraction were measured in the Laue geometry using a (+m, −n, +n) separated three‐crystal monochromator. Strain introduced in the sample preparation process gave a reduced oscillatory profile of a rocking curve although chemical etching recovered subsidiary peaks of the rocking curve. Strain frozen in as‐grown crystals also gave a reduced oscillatory‐profile, but a large number of oxygen precipitates produced by thermal annealing caused little reduction of subsidiary peaks.