There are three main enemies of plants - namely pathogens, pests and weeds and all these operate in natural conditions. It is a must to control the pathogens for proper growth of plants and yields from the crops. There may be many alternative means to control pathogens but biological control happens to be a much more useful alternative, as this is safer for the environment also. It is of course the reasons that biological control of plant diseases has attracted the attention of so many researchers and agencies. This paper deals with the concept of pathogens, biological control and its positive outcomes for the plants, ecology as well as human beings.