Apoptosis is a form of programmed cell death critical for the development and homeostasis of multicellular organisms. A key event within the mitochondrial pathway to apoptosis is the permeabilisation of the mitochondrial outer membrane (MOMP), a point of no return in apoptotic progression. This event is governed by a complex interplay of interactions between BCL-2 family members. The pro-apoptotic effector proteins Bak and Bax facilitate MOMP by creating a pore for cytochrome c release from mitochondria. Here we investigate how Bax is prevented from permeabilising the MOM by the pro-survival protein BCL-2. We have developed a strategy to purify a heterodimeric complex between Bax and BCL-2 and have probed its function using antagonising peptides and small molecules. Furthermore, we have obtained preliminary crystals of the complex and are in the process of optimising these to solve the structure by X-ray crystallography. These interactions and structural insights are of particular interest for drug discovery. This has recently been highlighted by successes in the development of Venetoclax, which targets BCL-2, to restore apoptosis in cancer. By improving our understanding of this heterodimeric Bax-BCL-2 complex we endeavor to guide new strategies to restore apoptosis in cancer cells.