5-Azacytidine has established activity in the treatment of adult acute leukemia. β-2'-Deoxythioguanosine is a new purine analog which produced 6 complete remissions in 25 adequately treated patients with acute myelogenous leukemia. A pilot study indicated that these 2 agents in combination were tolerable, and suggested a role for this combination in refractory acute leukemia. A cooperative clinical trial of this regimen by the Southeastern Cancer Study Group is reported. An interim analysis has been presented.