Asthma disease and its complications remain the cause of significant morbidity worldwide, representing a major burden for health care resources. Although potent anti-asthmatic drugs are available, most of them produce several toxicities, thus emphasizing the need to search for new alternatives. Therefore, the present study was designed to evaluate the anti-asthmatic activity of flowers extract of Nyctanthes Arbor-tristis using milk induced leucocytosis and eosinophilia in mice. Hydro-ethanolic extract of dried flower of Nyctanthes Arbor-tristis was prepared by maceration and used in the dose of 100 mg/kg and 200mg/kg; (p.o.). In-vivo model milk induced leucocytosis and eosinophilia mice were used for evaluating anti-asthamatic activity of the drug. The total leucocyte and eoisinophil count in disease control group was significantly higher as compared to hydro ethanolic extract of Nyctanthes arbor-tristis group IV, group V and Standard treatment group III with Mepyramine (< 0.05). Hydro ethanolic extract of Nyctanthes arbor-tristis at dose of 200mg/kg and Standard treatment with Mepyramine at dose of 8 mg/kg, p.o. shown statistical significant and positive inhibition was seen with leukocyte count 1640±142, 1230±175 and eosinophil count 68.83±1.22, 57±18.35. However, hydro-ethanolic extract of the drug showed a significant inhibition was observed in milk induced leucocytosis and eosinophilia. Thus, hydro-ethanolic extract of dried flower of Nyctanthes Arbor-tristis have significant anti-asthmatic activity.