Abstract: The invention relates to a process for preparing cis-N-methyl-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-1-naphthylamine, or racemic sertraline, corresponding to formula (I) in salt form, starting with 4-(3,4-dichlorophenyl)tetralone of formula (II) according to which (a) the 4-(3,4-dichlorophenyl)tetralone of formula (II) is reacted with N-methylformamide in the presence of formic acid, (b) the reaction medium obtained according to (a) is treated with a base, and (c) the racemic sertraline salt is separated out by selective crystallization with an acid. The invention also relates to N-methylformamide-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-1-naphthylamine and to its use to obtain racemic sertraline.