Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor super-family and signals via two death receptors, TRAIL-R1 and TRAIL-R2, and two decoy receptors, TRAIL-R3 and TRAIL-R4, differently expressed in normal and cancer cells. TRAIL is mainly studied for its capacity to induce apoptosis preferentially in cancer cells. TRAIL is expressed in a variety of human tissues, in particular in the lymphoid system, suggesting a strong physiological role in the innate immunity. This review will focus on TRAIL gene structure and regulation, protein folding, tissue expression and molecular signalling. Finally, the potential use of TRAIL as anticancer treatment alone or in combination therapy as well as the use of drugs which signal via TRAIL and its receptors will be analyzed.