Background: Celosia argentea is leafy herb commonly known as quail grass, feather cockscomb, and Lagos spinach belongs to the family Amaranthaceae. The Celosia argentea has great medicinal value, used in the treatment of fatigue, leucorrhoea, atherosclerosis and osteoporosis and the seeds have been used for reducing the “liver heat”, improving the eye sight, clearing wind heat and as an anti- inflammatory agent. In present study the flavonoids fraction from alcoholic extract of Celosia argentea was investigated for its anti-asthmatic potential by in vitro and in vivo techniques. Phytochemical evaluation detected methanolic fraction to be enriched in flavonoids. Hence, methanolic fraction was concentrated and loaded on a column of Sephadex using a step gradient of chloroform: methanol mixture (95:5, 90:10, 80:20,….100:0). The first fraction 95:5 gave distinct single band with the selected solvent system were further purified on HPLC column of MCI HP20. Fraction was collected using an automatic fraction collector and monitored by HPLC. Chromatographically pure compound were pooled, concentrated, and freeze-dried. Then the isolated compound was screened for antiasthmatic activity in rodents. Data were analyzed using ANOVA at p ≤ 0.05. Results: Isolated compound from celosia argentea (10mg/kg) significantly reduces paw volume at dose 10 mg/kg showed (0.180±0.005**) reduction of paw volume was comparable to standard drug Dexamethasone (0.160±0.005**).Also it significantly protect degranulation of mast cell at dose (10mg/kg) it gives 63.6% and Ketotifen fumarate at dose (1mg/kg, p.o.) gives 74.1% protection to mast cells. In case of histamine induced contraction in goat tracheal chain at concentration 30 μg/ml isolated compound of celosia argentea at 10μg/ml significantly inhibited the tracheal contraction which was compared with Chlorphenaramine maleate (1 μg/ml). This indicates that there was competitive antagonism between histamine and isolated compound of celosia argentea for H1 receptors present on the smooth muscle. Conclusion: The result indicates the isolated bioactive fraction of Celosia argentea responsible for its antiasthmatic effect which may be produce due to presence of quercetin flavonoid.