The present invention relates to the use of xenon as a neuroprotectant and/or as an inhibitor of synaptic plasticity. In a preferred aspect, the xenon acts as an NMDA antagonist. The present invention also provides a method of reducing the level of activation of the NMDA receptors in a mammal, the method comprising modulating the activity of the NMDA receptor by administering to the mammal a therapeutically effective amount of xenon, wherein said reduction achieves neuroprotection and/or an inhibition of synaptic plasticity. A further embodiment of the invention provides a pharmaceutical composition for providing neuroprotection and/or inhibition of synaptic plasticity, together with a process for the preparation thereof. Another aspect of the invention relates to a pharmaceutical composition suitable for providing neuroprotection, inhibiting synaptic plasticity or relieving neuropathic pain, said composition comprising xenon and a GABAergic agent admixed with a pharmaceutically acceptable carrier, excipient or diluent.