Abstract: A swallowable capsule for obtaining samples of gastric and/or intestinal fluids, the capsule defining an inner fluid receiving chamber having an inlet port which is normally sealed off from the exterior of the capsule by way of a blocking means including a mass the properties of which change upon contact with the suitable fluids present in the digestion tract, causing the means to communicate the inlet port with the outside of the capsule allowing a sample of the fluid to be aspirated into the chamber. Located within the chamber is a closing means normally maintained in a flow permitting position by a mass which glues the necessary parts of the closing means together in such a way that the parts cannot move, so that the action of the closing means is neutralized.