Wine bottle aging is extremely dependent on the oxygen barrier properties of closures. Kinetics of oxygen ingress through different closures into bottles was measured by a nondestructive colorimetric method from 0.25 to 2.5 mL of oxygen. After 12, 24, and 36 months of storage, only the control (glass bottle ampule) was airtight. Other closures displayed different oxygen ingress rates, which were clearly influenced by the closure type and were independent of bottle storage position (upright, laid down) for most of the closures tested, at least during the first 24 months of the experiment under controlled conditions. The oxygen ingress rates into bottles were lowest in screw caps and "technical" corks, intermediate in conventional natural cork stoppers, and highest in the synthetic closures.