The maturation and degradation of ribonucleic acid (RNA) into smaller nucleotides are carried out by a wide variety of cellular ribonucleases (RNases) which are also responsible for regulating the functional expression of several fundamental genes in living systems. They exist in eukaryotes to prokaryotes as well as in viruses. Structure, functions and catalytic mechanism of RNases have been well understood especially in Escherichia coli model. In addition to regulate the RNA metabolisms RNases demonstrate wide range of therapeutic effects also. They exhibit antitumor, antifungal, antiviral and immunosuppressive functions. Bovine pancreatic RNase (RNase A), bovine seminal RNase (BS-RNase), onconase and angiogenin are significant antitumor RNases. Onconase (Rampinase) is a stable amphibian homolog which displays significant cytotoxicity towards tumor cells and is the only ribonuclease which has reached up to the clinical levels. Onconase has proved potential therapeutic applications in the treatment of prostate, cervical, colon, breast and ovarian cancers as well as in lymphocytic leukaemia. The RNases demonstrate antiviral properties also. The Eosinophil Derived Neurotoxin (EDN) and the Eosinophil Cationic Protein (ECP) also known as RNases 2 and 3 are such RNases. The EDN shows broad range of antiviral activity towards several RNA viruses including HIV-1. Recombinant EDN constructs for example EDNsFv and rhEDN express cytotoxic effects against transfer receptor(s) expressing leukemia cells and respiratory syncytial virus. Some other RNases i.e., RNase 5, RNase 7 and RNase 8 have also been known for their antimicrobial effects indicating the role of RNases in immune defence. In the light of above, features and therapeutic applications of the typical RNases have been summerized in this review for the attention of healthcare research.