The possibilities for integration of biological control of plant pathogens into integrated pest management (IPM) systems is discussed. Biological control of plant pathogens is not as well developed as biological control of insects, this is due in a large part to the complexity of the environmental parameters that affect pathogen populations. However, there is a real potential to combine biological control with chemical, cultural and genetic methods currently used. The biological, sociological and economical limitations to integrating biological control into IPM systems are described. New research perspectives are presented that consider the importance of investigating agriculture as an ecosystem that contains population and community level structures.