A new transmission electron microscope method is reported where plan-view samples of Al0.3Ga0.7As/GaAs multilayers in (001) orientation and with a modulation wavelength of 210 Å are imaged using superlattice reflections. The results, obtained using both a large-angle diffraction technique and direct dark-field imaging, provide an accurate measurement of the multilayer period and also suggest the occurrence of local fluctuations in period, possibly of monolayer dimensions, which differ along [110] and [ ] directions. The method also provides some information on the composition profile in multilayers.