Omalizumab is a biological engineered molecule, targeting the Cepsilon3 domain of the IgE molecule. It binds with free IgE and prevents free IgE from attaching to high-affinity IgE receptor (FcepsilonRI) on effector cells such as mast cells, basophils and also on dendritic cells. The result is a blocking of mediator release from these cells and the inhibition of antigen presentation by dendritic cells. In addition, omalizumab downregulates FcepsilonRI expression on these effector cells. Omalizumab prevents early and late phase allergic reactions of skin and lungs. Omalizumab has been investigated extensively in moderate-to-severe asthma in adults and children. It effectively reduces rates of asthma exacerbation, emergency visits for asthma and hospital admissions among these patients. Currently, omalizumab is primarily indicated for patients, age 6 years and over, with moderate to severe asthma (GINA step 4). Omalizumab was investigated in patients with seasonal allergic rhinitis (to ragweed, birch and grass pollens) and has been found to improve rhinitis symptoms and to reduce medication use among these patients. Administered together with allergen immunotherapy, omalizumab reduced incidence of side effects and rates of anaphylaxis from allergen immunotherapy. Omalizumab has been investigated in the treatment of food allergy, atopic dermatitis and urticaria. Despite benefits observed from these initial trials, it further deserves investigations to clarify optimal conditions for use in these conditions. Side effects from omalizumab were few, however, it requires careful considerations in administration of this agent. An observational period (up to 2 hours after the first three doses) and the availability of auto-injectable epinephrine are recommended. Pharmacoeconomics of omalizumab is briefly reviewed. Omalizumab represents a major breakthrough of translational medicine in allergy.