Abstract: A series of new pyrazinamide analogues have been prepared. Report that 5-chloropyrazinamide [1] has different mode of action than pyrazinamide itself [2] promises good chance to reach new structure with high antimycobacterial activity and new action mechanism that is realy needed because of resisance increase [3] to drugs in current use. Dericatives of pyrazine-2,5-dicarbonitrile promise good starting point to further studies (best activity reached yet is 3-(3-chlorophenylamino)pyrazine-2,5-dicarbonitrile, with MIC = 8µmol.l-1 against classical TBC strains and with lower activity against atypical strains. Compared to pyrazinamide with MIC = 4µmol.l-1 against classical strains and no activity against atypical ones).