Dr Dhar has examined the constituents of a large number of indigenous plants and elucidated their chemistry, revealing a variety of new structures. In a systematic programme of screening Indian plants for biological activity, he has uncovered many active constituents worthy of further pursuit and exploitation. He has achieved significant results from his work on the mode of action of antibiotics carrying a heterocyclic moiety linked to a peptide sequence. He has developed a new synthesis of the internucleotide bond involving the use of pyrimidine and purine anhydronucleosides.