Protection of biodiversity is a corner stone in international environmental policies, and many plant and animal species are dependent on agricultural landscapes. If farms that provide high biodiversity are less efficient producers than others they might not survive in the long run and biodiversity values will be lost. In this paper we focus on the relationship between efficiency in commodity production and the provision of biodiversity for 266 Swedish farms. This is done by combining economic data with information on biodiversity such as the number of plant species provided by the farm. This enables us to explicitly model the relation between farm performance and observed biodiversity. Efficiency is estimated using Data Envelopment Analysis (DEA), and the efficiency scores are used in a second stage regression in order to assess the relationship between efficiency and biodiversity. The main result is a negative correlation between farm efficiency and biodiversity in the surrounding landscape. Thus, there is a risk of reduced faming in areas with high biodiversity in the agricultural landscape. This stresses the importance of properties common to all farms in biodiversity-rich areas and supports agricultural policies based on a landscape perspective and collective actions among farmers to provide eco-system services.