A drug delivery device includes a reservoir for containing a medical product, a distally projecting end-piece having an outer surface and a total length measured along a longitudinal axis of said end-piece, said end-piece defining an axial passageway for the transfer of said medical product contained in said reservoir, wherein a gripping surface is provided on a portion of said outer surface, said portion being located in a distal region of said end-piece, the length of said portion representing at most 40%, preferably less than 33%, of the total length of the end-piece. An assembly includes such a drug delivery device and an adaptor intended to be mounted onto the end-piece.
