Imines forms an important class of heterocyclic compounds such as1,4-Benzothiazine and its derivatives which shows wide range of biological activities such as antimicrobial, antifungal etc. Therefore, some new benzothiazine derivatives were synthesized by using benzanilide and substituted benzanilides with sulphene, generated in situ from methane sulphonyl chloride and triethylaminehydroxylchloride, as a starting material. The synthesized 1,4-benzothiazines (Ia -Va) were tested in vitro for their antifungal activity against Alternaria alternate, Curvularia lunata, Fusarium oxysporum and Myrothecium roridum by employing the standard technique of spore germination inhibition at various concertation’s. Some of the compounds have shown promising antifungal activity against test fungi.