Bamboo fibres offer numerous over synthetic fibre as reinforcing filler for polymer composites. Yet the hydrophilic nature of bamboo fibres with high moisture absorption results in incompatibility in between bamboo fibres and unsaturated polyester resin. A systematic study was carried out to investigate the effects of Montmorillonite (MMT) nanoclay on the mechanical properties and water sorption properties of nanoclay modified polyester nanocomposite (NPC).