Thousands of people with really serious cases of asthma could get help from a new medicine.
The drug is called Xolair, and it was created especially for people who have really bad allergic asthma that other types of medicine can't tackle.
The drug may be able to help as many as 10,000 of the 5.2m people in the UK with asthma, according to experts.
About 1,400 people die from severe asthma each year in the UK, and a further 69,000 go to hospital.
The drug is given to sufferers by an injection from a doctor every two-four weeks, and is used in addition to other medicine being taken.
Only patients older than 12 will be prescribed the drug, and they have to have very bad problems with asthma too.
The drug is already being used in a number of other countries, including the US, Australia, Canada and Brazil.
The chairman of the British Lung Foundation, Dr Mark Britton, said: "It's a major new step in the treatment of allergic asthma."