The selective formation of p-xylene, 1, 2, 4-trimethylbenzene and 1, 2, 4, 5-tetramethylbenzene by shape selective alkylation of methylbenzenes with methanol on HZSM-5 zeolite catalysts was reviewed. In the alkylation of toluene with methanol on HZSM-5, p-xylene was selectively produced in the initial stages of the alkylation. However, the p-xylene first formed was isomerized to m- and o-isomers on the strong acid sites of HZSM-5. So, for selective formation of p-xylene, modifying HZSM-5 by MgO to poison such strong acid sites was found very effective. The pore structure of HZSM-5 was suitable for selective formation of 1, 2, 4-trimethylbenzene by alkylation of xylene with methanol. On nonmodified HZSM-5 catalyst, 1, 2, 4-trimethylbenzene was synthesized with high selectivity. By the shape selective alkylation of 1, 2, 4-trimethylbenzene with methanol on HZSM-5 catalyst, 1, 2, 4, 5-tetramethylbenzene could highly be formed selectively. Small amounts of products with large molecular sizes, such as tetramethyl-benzenes, except 1, 2, 4, 5-isomer, trimethylbenzenes, except 1, 2, 4-isomer, were formed only on the acid sites on the exterior surface of HZSM-5 crystallites. When the acid sites on the exterior surface were poisoned by 2, 4-dimethylquinoline or were removed by treatment with SiCl₄, the selectivity for 1, 2, 4, 5-tetramethylbenzene formation could be improved.