Hepatic veno-occlusive disease (VOD) is frequently linked to stem cell transplantation (SCT), mainly related to the conditioning regime, and contributes to considerable morbidity and mortality. However, pyrrolizidine alkaloid (PA)-induced VOD has long been overlooked. The pathogenesis of VOD remains poorly understood; studies suggest that endothelial cell injury, cytokines and haemostatic derangement are all involved in the pathogenesis of VOD. Until recently, treatment options have been limited and no uniformly effective therapy has been established. Thus, treatment is largely supportive and symptomatic. Ongoing work, including development of new animal models and clinical studies, is needed to help us fully understand the pathogenesis of VOD and enable us to devise effective solutions. Furthermore, it is strongly advised that supervisory measures be taken to standardise the use of herbal medication.