New potent lipoxygenase inhibitors which are 1H-pyrido-[2,3-b][1,4] thiazines are disclosed. The new thiazines are of the formula ##STR1## in which R.sup.1 denotes hydrogen, halogen, optionally substituted alkyl or alkoxy or the group ##STR2## in which R.sup.5 and R.sup.6 are identical or different and denote hydrogen, optionally substituted alkyl or aryl, or can be linked to form a 5- or 6-membered heterocyclic ring,R.sup.2 and R.sup.3 are identical or different and denote hydrogen or optionally substituted alkyl or alkoxy andR.sup.4 denotes hydroxyl, the group ##STR3## in which R.sup.5 and R.sup.6 have the abovementioned meaning, or, in the case where R.sup.3 denotes hydrogen or optionally substituted alkoxy, also denotes optionally substituted alkoxy.