Girls aged 12 and 13 across the UK are being given the chance to have a new, possibly life-saving, injection.
The injections are to help stop them getting a type of cancer called cervical cancer when they're older.
It affects almost 3,000 women every year, and has been in the headlines recently because TV celeb Jade Goody has just been told she's got it.
Cervical cancer comes from a virus called HPV, and scientists say the jab could prevent girls from getting it.
The virus infects the entrance to the womb, so boys don't need the jab because they don't get this kind of cancer.
Every year around 2,800 women are diagnosed with cervical cancer in Britain.
Jade's been told she has cervical cancer
Most of them get better after having treatment from doctors, but more than 1,000 die, and others are left unable to have children.
Some pupils in Northern Ireland and Scotland have already started having the jabs.
But if you're a girl aged 12 or 13 and haven't had it yet, your school will tell you when and where you can get it.
Nearly all experts think it's a good idea, but your parents get the final say on whether you have the injection.