The purpose of this extension study is to assess the long-term safety and tolerability of omalizumab as an add-on therapy in Japanese pediatric patients (6 to 15 years of age) with inadequately controlled allergic asthma despite current recommended treatment by providing continued treatment with omalizumab to patients who have previously completed the core study.

Inclusion Criteria:

• Patients who completed the core study (IGE025B1301) and who in the investigator's clinical judgment could benefit from continuous treatment of the study drug.

Exclusion Criteria:

• Patients who currently have diagnosed cancer, are currently being investigated for possible cancer or have any history of cancer.
• Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, UNLESS they are: women whose career, lifestyle, or sexual orientation precludes intercourse with a male partner; women whose partners have been sterilized by vasectomy or other means; using a highly effective method of birth control; or agreeing on total abstinence and the investigator also judges that the age, career lifestyle or sexual orientation of the patient ensures compliance.
• With clinically significant uncontrolled systemic disease (eg: infection, hematological disease, renal, hepatic, coronary heart disease or other cardiovascular disease, cerebro-vascular, endocrinologic or gastrointestinal disease) after the treatment period of the core study.
• Patients with a history of major protocol violations during the core study and who are considered potentially unreliable as judged by the investigator at each site.