The book “Microbiology, Phycology, Mycology, Lichenology and Plant Pathology” is a comprehensive treatment according to the latest syllabi prescribed in the universities for undergraduate programs in Botany. The topics are arranged with a view that the students can acquire clear concept on the structure, reproduction and economic importance of lower organisms. The students will get an insight of nature around him. The topics are treated on a general basis with relevant specific points. The systematic positions of lower organisms based in accepted systems, diversity in structure and life cycle are clearly explained with relevant illustrations.