The present study attempts to examine the impacts of rice-prawn gher farming on land tenure system in southwest Bangladesh. Primary data and case studies are used in the present study. The land tenure system has changed after the introduction of rice-prawn gher farming system from traditional sharecropping system to fixed rent. Natural risks, calamities and uncertain yield of prawn are the main factors that enforced the land tenure system from sharecropping to fixed rent. The amount of rent paid is usually determined by several factors including the location of the land, size and quality of gher farm and the relationship between the landlord and the tenant and the amount varies from Tk 20,000 to Tk 25,000 per hectare. The amount of rent and time also depend on the relationship between the landlord and the tenant.