O-Methyl-N-nitroisourea is primarily used in organic synthesis as a potent alkylating agent. It is particularly valuable in the preparation of various nitrogen-containing compounds, including amines and heterocycles, which are essential intermediates in pharmaceuticals and agrochemicals. Its ability to introduce methyl groups into target molecules makes it a key reagent in modifying chemical structures to enhance biological activity or alter physical properties. Additionally, it has been utilized in research for studying mutagenesis and carcinogenesis due to its strong alkylating properties, which can induce DNA damage. Proper handling is crucial due to its high reactivity and potential toxicity.