Abstract A series of new N-nitroso-2, 6-dicarbethoxy-3, 5-diaryltetrahydro-1, 4-thiazine-1, 1- dioxides 4a–r were synthesized and evaluated for antibacterial and antifungal activity. Most of them registered significant antibacterial and antifungal activity. The newly synthesized compounds have been characterized on the basis of elemental analysis, infrared, and nuclear magnetic resonance spectroscopic data.