Ailanthus excelsa (Stem bark) are used in folk medicine for a treatment of inflammation, arthritis, expectorant, stimulant and asthma. Acute toxicity study of A. excelsa stem bark was performed on mice (Swiss) and albino rats (Wistar strain),given single doses 1,10, 50, 100 ,1000 and 2000mg/kg,po. showed normal behavior and no mortality up to 14 days except 500,1000 and 2000mg/kg dose 20%, 60.0 % &100% mortality recorded respectively. A. excelsa (10- 50x7days or 10,50 and100mg/kg, po single dose ), pretreatment time , 60 min showed significant sub-acute anti-inflammatory protection against Cotton pellet induced granuloma formation, no analgesic activity, pentobarbitone induced sleeping time reduced insignificantly, decreased swim stress immobility in mice indicating some degree of antidepressant activity. A. excelsa exhibited significant inhibitory activity against castor oil -induced diarrhoea and significant reduction in gastrointestinal motility in the activated charcoal meal in rats. The steroids, glycosides , alkaloids, and flavonoids present in the plant appear to be of chemotherapeutic interest.