Farmers in Kerala extensively used bio inoculants for the management of diseases and for promotion of growth in black pepper, vanilla, cardamom, betel vine, ginger, rice and vegetables. The study entitled “Constraints in black pepper (Piper nigrum L.) production using microbial inoculants in Idukki district of Kerala” is worth due to the role of microbial inoculants in sustainable agriculture presumes special significance. The present study which is an attempt to understand the challenges of MI application in black pepper production in Idukki district. The major constraints in the adoption of MI are lack of awareness about practical utility and lack of technical expertise on MI. Farmers in the study area are incognizant about all types of MI. The narrow knowledge about this technology was the major challenge which has led to the adoption of only few types of bio inoculants.