7 - oxabicycloheptane hydroxamic acid derivatives are disclosed having the general formula ## str1 ## wherein r 1 is hydrogen , lower alkyl , aryl , aralkyl or alkenyl ; r 2 is hydrogen , lower alkyl , alkanoyl or aroyl ; r 3 is lower alkyl , alkenyl or alkynyl ; a is -- ch 2 -- ch ═ ch -- or a single bond ; and n is an integer from 0 to 9 , with the proviso that when a is a single bond , n is an integer from 1 to 9 ; and including all stereoisomers and pharmaceutically acceptable salts thereof . these new compounds have been found to simultaneously inhibit the arachidonic acid enzymes cyclooxygenase and 5 - lipoxygenase and are therefore useful as antiinflammatory , antiasthma and antipsoriatic agents .