The synthesis of six 2-methyl-3-arylidenoaminocyclohexeno [b] thieno [2,3-d]-3,4-dihydropyrimidin-4-ones is described. The biological activity of these new compounds was screened against several Gram-positive and Gram-negative bacteria. The activity of our compounds is 5 to 320 fold less active than ciprofloxacin.