Land tenure security is important to agricultural development, especially in developing countries. Viet Nam’s land law has been significantly improved since its economic reform starting in 1986 and made a great contribution to the enhancement of security of farmers’ land-use rights. The breadth of farmers’ land-use rights has been widen including better substantive rights to land such as right to control arable land  independently, to transfer land-use rights and to receive fair compensation over land expropriation. More importantly, the duration of  land-use rights has been prolonged for fifty years and can be renewed automatically. However, in a transition to a modern economy as emerging in Viet Nam, there remain challenges to the security of farmers’ land-use rights such as limitation of arable landholding ceiling, unnecessary procedural provisions of renewals, and no clear-cut transition to a modern thinking of law-makers for land use management. These challenges requires a further reform of the land law in order to encourage more effective land use for agricultural development and bring larger economic benefits to small farmers.