A series of oxadiazole mannich bases were synthesized by reacting oxadiazole derivatives, dapsone and appropriate aldehyde in the presence of methanol. The synthesized compounds were evaluated for antimycobacterial activity against M. tuberculosis H37Rv and INH resistant M. tuberculosis. Among the synthesized compounds, compound (4) 3-{2-furyl [4-(4-{2-furyl [5-(2-naphthyloxymethyl)-2-thioxo-2, 3-dihydro-1, 3, 4-oxadiazol-3-yl] ...