Heterocyclic chemistry being an important branch of chemistry includes many ring structures with heteroatoms such as nitrogen, oxygen, and sulfur. Quinazoline is an important nitrogen containing benzofused heterocycle and has several therapeutic actions such as antimalarial, antimicrobial, anticancer, and anticonvulsant. Quinazoline was first isolated from alkaloid vasicine. Vasicine, deoxyvasicine, tryptanthrin, and rutecarpine are some of the potent naturally occurring quinazolines. Substitutions on different positions of quinazoline ring lead to different activities. Detailed survey of activities of quinazoline such as anticancer, anticonvulsant, antifungal, antibacterial, and antidiabetic according to structure–activity relationship and marketed preparations containing quinazoline as an active moiety is described in this review.