An in-bottle aerator for mixing the oxygen in the air with wine as the wine is poured from its bottle. The aerator has at least one air ingress channel extending from one end of the aerator to the other allowing air into the bottle to displace wine exiting the bottle. Air mixing channels draw air from outside the bottle and direct that air to lateral channels that intersect a central flow channel extending from one end of the bottle to another. The air mixing and air ingress channels are preferably arranged to allow the user to pour and aerate wine at the same time and with the bottle in any orientation about its axis. The aerator may be a separately formed component that can be inserted into the bottle by the bottle manufacturer, by a wine bottler or by an enduser. Alternatively, the aerator may be wholly or partly formed as part of the neck of the bottle. A completely and integrally formed aerator may be formed a part of a plastic wine bottle. For or plastic or glass wine bottles aeration channels may be formed on the internal surface of the neck of the bottle and an insert can be used to complete the within bottle aerator by the insertion (by the bottle manufacturer, by a wine bottler or by an enduser) of an aerator component having additional channels formed therein.