A series of hindered phenolic 1,3-benzoxathioles (7a-l) were prepared and investigated for biological properties. Many compounds had LPO-lowering, antisuperoxide inhibiting, SRS-A inhibiting, and 5-lipoxygenase inhibiting activities. Among them, 5-hydroxy-4,6,7-trimethyl-2-propyl-1,3-benzoxathiole (7d) and 3-(5-hydroxy-4,6,7-trimethyl-1,3-benzoxathiol-2-yl)propanol (7j) were most potent in SRS-A inhibiting and 5-lipoxygenase inhibiting activities, respectively, and were selected for further development as candidate drugs for the treatment of asthma.