Biological control, particularly by entomopathogenic fungi is important for reducing the population density of pests in Integrated Pest Management (IPM) programs. The compatibility of entomopathogenic fungi with crop production techniques such as the use of insecticides is needed to understand, which may inhibit to a smaller or larger extent the development and reproduction of pathogen. The efficacy of microbial control agent could be enhanced by applying them in conjunction with reduced rates of insecticides. The interaction between these control agents could be additive, synergistic or antagonistic. Synergistic interactions would enhance the effectiveness of the microbial control agent while reducing the adverse effects of pesticides. In this review, we will describe the compatibility of entomopathogenic fungus, Beauveria bassiana and botanical insecticide, neem.