In search of new antileukopenia agents, twenty dithiolopyrrolone derivatives were synthesized and evaluated for their leukocyte-increasing activities in normal mice. Among the synthesized compounds 4-23, compounds 5 and 6 showed significant leukocyte-increasing activity ( p < 0.01), and compounds 4, 9 and 16 had a moderate effect ( p < 0.05). Compound 5 also displayed stronger leukocyte-increasing activity than that of the positive recombinant human granulocyte colony stimulating factor (rhG-CSF). Above all, compound 5 would be a potential antileukopenia agent which deserved further research.