An American company says it has cloned a human embryo for the first time.
The company said it didn't do it to create a person but to research into how it can be used to treat diseases like cancer and Aids.
Human embryos contain stem cells which can be used to create almost any human tissue.
The announcement has caused controversy because many people think it's wrong to try to clone humans.
For an actual person to be created the cloned embryo would have to be implanted into a woman who would then have to give birth.
The High Court in Britain recently said a loophole in the law meant it's not illegal to clone humans here.
So new laws are being made to ban it, but cloning for research reasons would still be allowed.
But some people say all forms of human cloning, even for medical research should be banned.
The most famous animal clone is Dolly the sheep who was created in 1997 at the Roslin Institute in Edinburgh, Scotland.