This contribution suggests a classification of French prepositions - à, après, avant, avec, chez, contre, dans, de, depuis, derrière, dès, devant, en, entre, envers, hors, jusque, par, parmi, pendant, pour, sans, selon, sous, sur, vers - according to the syntactical properties of their object (i.e. depending on the constituent they sub-categorize : noun phrase, prepositional phrase, sentence, infinitive, zero complement, adverb, adjective). These combinatorial properties allow to group, following the syntax, prepositions which would not spontaneously have been included following their semantics (chez, entre, envers, parmi, sous on one hand, avant, pour on the other hand), and to invalidate the semantic groupings usually performed (sur/sous, après/avant...). The observation of the distribution will throw light on this classification.