This study assessed the diversity composition and density of plant species at Dammam Region, Eastern Province, Saudi Arabia. Plant diversity is a vital component of any ecosystem. It is a wellknown fact that, worldwide, thousands of plant species are endangered and facing extinction with the current trend of their influence and destruction. Changes in the structure of the assortment of resources lessen plant community's opportunity to respond to new problems and occasions. Plant diversity is facing danger of new plant diseases or pests, species extinction, climatic changes and other obstructions. A survey of 12 different sites was done and botanic biodiversity was evaluated. The plant diversity was evaluated by applying different methods namely: relative abundance index, species richness D* index and Shannon-Weaver index. It is clear that many plant species and habitats of Dammam area are subjected to severe disturbance due to new constructions without environmental impact assessment.