The prepn. of succinylcholine halide derivs. of formula (I) comprises (a) reacting a succinic acid dialkyl ester of formula (II) with excess dimethylamino methanol in the presence of alkali-alcoholates or -amides as the catalyst and continuously distilling off the alcohol produced in the reaction; (b) recovering the excess dimethylamino ethanol inactivating the catalyst and filtering it off; and (c) reacting the succinic acid bis-(2-dimethylaminoethyl ester) of formula (III) formed with a methyl...