Nitrosourea is both the name of a molecule, and a class of compounds that include a nitroso (R-NO) group and a urea.

Examples include:

Nitrosourea compounds are DNA alkylating agents and are often used in chemotherapy. They are lipophilic and thus can cross the blood–brain barrier, making them useful in the treatment of brain tumors such as glioblastoma multiforme.

Some nitrosoureas (e.g. lomustine) have been associated with the development of interstitial lung disease.