Every year more and more rhinos are being killed for their horns.
In some Asian countries like China and Vietnam many people believe that the animal's horn can be used as a medicine to treat illnesses.
But scientists say that this isn't true and that the horns can't cure disease.
The UK government is now leading a global campaign asking world leaders to explain to their people why they shouldn't buy the items.
In 2007 only 13 rhinos were killed by poachers in South Africa, but since the start of 2011 over 200 have died for their horns.
Experts reckon that in some countries, a rhino horn can be sold for even more than diamonds or gold.
The poachers can earn up to £50,000 a kilogram for a horn; which is why it's really hard to get them to stop.
By getting leaders to explain that the horns don't help to treat diseases, it's hoped that there will be less demand for the items.
Rhinos are among the most endangered animals in the world, with four out of the five species of rhino under threat of extinction.