A nursing bottle's interior remains at atmospheric pressure during use so a baby nursing from it is not forced to suck so hard that air is inadvertently swallowed. The nursing bottle has a container adapted to contain liquid at its bottom and having an air space at its top with a first opening at its top for the reception of a nipple cap, a reservoir located adjacent to the air space at the top of the container, a vertical liquid conduit from the bottom of the container to the bottom of the reservoir, and an air conduit from outside the bottle to a point in the reservoir where an air space exists when the bottle is filled with liquid and inverted. The reservoir has a volume greater than the volume of the liquid conduit and has a shape which slopes downwardly to the point of communication with the conduit so that any liquid in the reservoir drains out of the reservoir when the bottle is in the upright position and is retained in the reservoir when the bottle is in the inverted position. When liquid is added to the nursing bottle and the nursing bottle is fitted with a nipple, the liquid level in the container and in the conduit are the same. Furthermore, when the nursing bottle is inverted, the liquid from the liquid conduit flows into the reservoir and an open air passage is established through the air conduit-reservoir-liquid conduit to carry ambient air into the container.