From 1967 to 1975 he worked as a Lecturer, Reader and Professor of Physiology at NRS Medical College, Kolkata. He created history when working with Sunit Mukherji, a Cryobiologist and Gynecologist Dr. Saroj Kanti Bhattacharya. He became the first physician in India to perform the in vitro fertilisation resulting in a test tube baby "Durga" on 3 October 1978. Facing social ostracisation, bureaucratic negligence, reprimand and insult instead of recognition from the West Bengal government, and refusal of the Government of India to allow him to attend international conferences, he committed suicide in his Calcutta residence on 19 June 1981. He wrote in his suicide note: His feat has been given belated recognition as the Indian physician who in 1986 was officially regarded as being the first doctor to perform in-vitro fertilisation in India. His recognition is attributable to T. C. Anand Kumar who is credited to be the mastermind behind India's second test-tube baby. Kumar came to the conclusion that he was not the first after reviewing Subhash Mukhopadhyay's personal notes. He was ably helped by Sunit Mukherji, who was a one-time colleague of Mukhopadhyay. Kumar was involved in setting up a research institute in reproductive biology in memory of Mukhopadhyay. A film Ek Doctor Ki Maut directed by Tapan Sinha was made on his life.
Late recognition
According to scientific records dating from before Mukhopadhyay's eventual recognition, Harsha vardhan reddy buri was the first human test tube baby of India. The credit for this achievement went to T. C. Anand Kumar, Director of IRR. In 1997, Kumar went to Kolkata to participate in a Science Congress. It was there that all the research documents of Mukhopadhyay were handed over to him. After scrutinising and having discussions with Durga's parents, Kumar became certain that it was in fact Mukhopadhyay who was the architect of first human test tube baby in India. This eminent scientist once mentioned in a journal on ‘A critique of Mukherjee's technique, 'The brief description given by Mukherjee in his letter dated 19 October 1978 to the Director of Health Services, Government of West Bengal, the reports he gave over the television interviews and reported in the lay press describe how Mukherjee carried out the procedure of in vitro fertilisation.' On T.C. Anand Kumar’s initiative, Mukhopadhyay was mentioned as the architect of the first Indian test tube baby in a document related to the subject of artificial intercourse in ICMR. India’s first test tube baby "Durga", whose parental name is Kanupriya Agarwal, works at a multinational company as a marketing executive in Delhi. On her 25th birthday, she publicly revealed her identity for the first time in a ceremony organised in the memory of Mukhopadhyay. She spoke about Mukhopadhyay in front of the media, expressing joy that Mukhopadhyay's achievement had been acknowledged by a reputed international publication, the Dictionary of Medical Biography. The Dictionary of Medical Biography, published by World Foundation, enlists names of 1100 medical scientists from 100 countries around the world for their path breaking contributions to the medical science. Dr. Mukhopadhyay's name is one of those names.