Objective To establish an animal model in which both early-phase asthmatic response (EAR) and late-phase asthmatic response (LAR) can be observed after sensitization and subsequent inhalation challenge with ovalbumin (OVA). Animals were conscious with no narcotic used, unrestricted, and fed ad libitum. Methods Sixty-six SPF 6-8-week old male Brown Norway rats were divided into eleven equal groups. All groups of rats except normal control group were injected subcutaneously with 0.4 mL (sc in back, 2 sites, 0.2 mL/site) OVA or OVA + Al(OH)₃ solution on day 0 and day 5. Four groups were given OVA only at the dose of 0.01, 0.1, 1.0 or 10.0 mg/rat, five groups were given OVA + Al(OH)₃ powder at the dose of 0.1+100, 1.0+100, 10.0+100, 1.0+52 and 1.0+4 mg/rat, one group was given OVA+Al(OH)₃ gel at the dose of 10.0+4 mg/rat. Normal control group was injected subcutaneously with the same volume of saline. All the groups were challenged for 10 minutes with 5 mL 5%OVA aerosol on day 37. Enhanced pause (Penh) was recorded for 16 hours in a whole-body plethysmography system after challenge. Specific IgE of the serum samples on day 0, 7, 14, 21, 28, 35, 38 were measured by ELISA. Pulmonary pathological changes were observed using HE staining. Results Compared with the normal control group, immunized rats except the group given 0.01 mg OVA produced specific IgE (P<0.05), and the content of IgE grew sharply after 7 days, and always kept growing until 5 weeks. The whole course of asthma exacerbation was recorded successfully. The rats developed EAR and/or LAR within 16 hours following OVA challenge. Especially the groups injected with 10 mg OVA and 100 mg Al(OH)₃ or 4 mg Al(OH)₃ gel showed steady pattern of biphasic airway responses and their EAR or LAR peak, and the area under the curve were increased significantly compared with those of the normal control group (P<0.05). Inflammation characterized by eosinophil infiltration was observed in the rat lung of model group (OVA 10.0 & Al(OH)₃ 100 group as a representative case). Conclusions In this work we successfully developed a new model using conscious rats, and the whole time course of asthma exacerbation in this model can be observed after OVA challenge. This model may become a useful tool for further asthma research.