The clinical syndrome of VOD is a frequent cause of nonrelapse mortality among patients receiving high-dose cytoreductive regimens. Patients likely to develop VOD have existing liver dysfunction, evidence of infection before conditioning, tend to receive more intensive preparative regimens, and often receive marrow from alternative donors. Therapeutic drug monitoring of busulfan and pharmacokinetic dose adjustments appear to be useful in reducing the incidence of VOD in patients receiving this agent. Data are contradictory as regards whether pharmacologic prophylaxis is effective. Patients who will develop severe VOD are characterized by a rapid increase in serum bilirubin as well as weight. Supportive management of these patients should attempt to preserve respiratory as well as renal function, sometimes a very difficult task. Treatment with recombinant tissue plasminogen activator has promise. However, given its potential for toxicity, a prospective randomized trial should be performed. Hopefully, as more data regarding the molecular and cellular mechanisms of this illness are elucidated, more thoughtful prevention strategies will be developed. This will be necessary, particularly as newer, more intensive preparative regimens are being developed, as access to alternative donors increases, and as more diseases will be treated with this approach.