Dr Hans Blix said Iraq has got rid of some its weapons but admitted that there were also some difficulties.
The speech is important because it could be a deciding factor in whether a war in Iraq starts.
Dr Blix last reported to the United Nations in January, and he said that since then Iraq has offered more help to his team of inspectors.
But he added that Iraq was not helping as quickly as the UN team wanted.
He also said that it would take months to find out if Iraq has actually got rid of all the weapons that they've been told to.