A new series of 2-(5-nitro-2-furyl)-1,3,4-thiadiazole-2-sulfide, sulfoxide and sulfones were synthesized and evaluated for in vitro antituberculosis activity against Mycobacterium tuberculosis strain H37Rv using the radiometric BACTEC 460-TB methodology. Active compounds were also screened by serial dilution to assess toxicity to a VERO cell line. The results indicate that some compounds exhibited a good antituberculosis activity and the ethylthio analogue (5b) was the most active compound (MIC = 0.78 microg ml(-1)). Also, the cytotoxic effects indicate that compound 5b was the least toxic compound.