In connection with the search for new antituberculotics, the present authors prepared a group of derivatives of 3-(4-ethoxythiocarbonylphenyl)-2H-benzoxazin-2,4(3H)-dithione and 3-(4-ethoxythiocarbonylphenyl)- 4-thioxy-2H-benzoxazin-2,4(3H)-one. The modifications of substituents were carried out on the benzoxazine ring. The study was based on the present authors’ previous assumption that the substitution of the oxo group for the thioxo group was connected with an increase in antimycobacterial activity. The prepared substances were evaluated by the activity against Mycobacterium tuberculosis, Mycobacterium kansasii, and Mycobacterium avium. However, it was concluded that there was no assumed increase in antimycobacterial activity in the groups of 3-(4-ethoxythiocarbonylphenyl)-4-thioxy-2H-benzoxazin-2,4(3H)-one and 3-(4-ethoxythiocarbonylphenyl)- 2H-benzoxazin-2,4(3H)-dithione derivatives.

        Key words: benzoxazin – mycobacterium – tuberculostatics – thiones