The effects of interaction between acetyl salicylic acid [300 mg/kgm/day orally for 2 weeks] and ibuprofen [100 mg/kgm/day orally for 2 weeks] were studied in albino rats rendered arthritic by intradermal injection of mycobactrium butyricum. The fluorimetric estimation of plasma cortisol level showed significant elevation following acetyl salicylic acid administration and also following combined ibuprofen and acetyl salicylic acid administration but to a less extent, while ibuprofen alone failed to produce any significant change. Analgesic activity was assessed by analgesymeter test. Acetyl salicylic acid and ibuprofen given seperately or conceurrently produced a highly significant analgesic action which did not differ statistically in various groups. Anti-inflammatory activity was assessed by the paw oedema test, the anti-inflammatory action of ibuprofen was statistically more marked than that of acetyl salicylic acid, but was more or less similar to the effect of concurrent drug administration. It could be concluded that the analgesic action of combined acetyl salicylic acid and ibuprofen administration was not superior to either drug when given alone, and the anti-inflammatory action of combined administration did not differ from that of ibuprofen alone, thus one could suggest that, this form of combined drug therapy has no advantage over ibuprofen alone