A process for the preparation of zeolites of the ZSM-5 structural type from a mixture of SiO.sub.2 and Al(OH).sub.3 by hydrothermal crystallization in an aqueous amine solution, in the absence of alkali, at from 100.degree. to 200.degree. C., wherein the crystallization is carried out in the presence of a triamine, tetraamine and/or higher amine and the reaction mixture is formulated to have an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio defined by an equation which involves the chain length and number of amine groups of the amine employed, as well as to have certain molar ratios of H.sub.2 O/amine and amine/Al.sub.2 O.sub.3, and the use of these zeolites as catalysts for the conversion of alcohols and/or dialkyl ethers to olefins and/or aromatics