Dr. R.S. Mehrotra was born on 4th January, 1937 in Village Anantram, District Etawah, U.P. He did his M.Sc and Ph.D from the University of Saugar, Sagar (Now known as Dr. Hari Singh Gaur University), M.P. in the year 1958 and 1961 respectively. For his  Ph.D degree he worked on the foot rot and leaf rot of Piper betle and their control under the supervision of Late Prof. S:B. Saksena. He joined the University of Saugar, M.P., in the year 1964 as Assistant Professor and then later shifted to Kurukshetra University, Kurukshetra in year 1970 as Reader then Professor in the year 1978. He retired from Kurukshetra University in the year 1997. He was Post Doctoral Fellow at the University of Western Ontario, London, Ontario, Canada in the years 1968-1970 and worked in collaboration with late Prof. C.J. Hickman on the biology of Phytophthora Zoospores in soil using fluorescent brighteners. and fluorescent Microscopy. He was also a Fulbright Fellow at the University of California, USA Riverside campus for a short duration in the year 1979 and worked in collaboration with world authority on Phytophthora, Prof. G.A. Zentmyer.

Professor Mehrotra is a Fellow of the National Academy of Sciences (Allahabad). He was elected President of the Indian Phytopathological Society in the year 1.990 and delivered his Presidential address entitled "Status of Phytophthora Research in India". He was also elected President of the Indian Society of Plant Pathologists in the year 1992 and President of the Mycological Society of India in the year 1996. He was elected President of the Botany Section of Indian Science Congress in the year 1997 and is a recipient of the Birbal Sahni Gold Medal of the Indian Botanical Society in the year 1998.

The main thrust of his research work has been on Phytophthora diseases of various crops and fungal soil borne diseases and bio-control of plant pathogens. He has authored four books "Plant Pathology" first published in 1980 by Tata McGraw Hill, New Delhi, Second edition with Prof. A. Aggarwal in 2001. "An introduction to Mycology" with Prof. K.R. Aneja first published in 1990 by Wiley Eastern, New Delhi, a monograph on "Phytophthora Diseases in India" co- authored with Prof. A. Aggarwal in 2001 and published by Bishen Singh and Mahendra Pal Singh, Dehradun and recently "Principles of Microbiology" with Prof. Geeta Sumbali in 2009 and published by Tata McGraw Hill Education Private Limited, New Delhi. Professor Mehrotra has written several review articles and published more than 200 research papers in national and international journals.