Isatin (1H-indole-2,3-dione) and its derivatives are responsible for a broad spectrum of biological activities. Among these the cytotoxic and antineoplastic properties have been the most widely reported. The synthetic versatility of the isatin, due to its privileged scaffold, has led to the generation of a large number of structurally diverse derivatives which include analogues derived from either mono-, di-, and trisubstitution of the aryl ring A, and/or those obtained by derivatisation of the isatin nitrogen and C2/C3 carbonyl moieties. These compounds inhibit cancer cell proliferation and tumour growth via interaction with a variety of intracellular targets such as DNA, telomerase, tubulin, P-glycoprotein, protein kinases and phosphatases. Herein we review recent highlights in the development of isatin-based compounds as anticancer agents with a particular focus on the cytotoxicity and structure activity relationships.