Abstract: A tamper-proof bottle stopper intended to be used for closing wine bottles. The stopper means is of a composite nature and includes a stopper body having an integral upper flange portion which is situated in the closed position above the annular end surface of the neck of a bottle and abuts against the latter when the stopper body proper is pressed into the neck. The upper portion of the stopper body is corrugated or fluted on the radially outer surface thereof. The stopper body defines a cavity open at the upper end and closed at the lower end into which a gas-tight stopper insert is placed. The composite stopper means further includes a fluted cap that engages and coacts with the fluted portion of the stopper body so as to prevent a rotary motion of the cap relative to the stopper body. The cap is provided with a skirt projecting downwardly on the outer surface of the neck of a bottle.