The positions of acetyl groups introduced by Friedel-Crafts reactions into 2,3-diphenylbenzofuran and its derivatives monomethylated in the 5,6 and 7 positions and dimethylated in the 5,6 positions were determined by means of single and double resonance NMR spectra. It was found that the first acetyl group occupies position 6 for all 6-unmethylated compounds and position 5 for 6-methylated compounds. The next two acetyl groups enter the para positions (4′ and 4″) of the phenyl groups with the same probability. When positions 5 and 6 are methylated the acetyl group enters positions 7,4′ and 4″ which are found to be of almost equal reactivity. The NMR parameters of compounds studied are listed.