More than 200 Holocaust cartoons from around the world are on display at a museum in the Iranian capital, Tehran.
The drawings were chosen from entries in a competition
Organisers of the exhibition say they are testing the West's commitment to freedom of speech.
A competition to choose the drawings was announced in February, in response to caricatures of the Prophet Muhammad published by European newspapers.
Israel's Holocaust authority, Yad Vashem, criticised the exhibition, calling it a "flashing red light".
The drawings were chosen from nearly 1,200 entries received from various countries including the United States, Indonesia and Turkey.
One of the cartoons shows the Statue of Liberty holding a book on the Holocaust in one hand and giving a Nazi salute with the other.
The Iran Cartoon Organisation and Hamshahri newspaper are putting on the exhibition.
Organiser Masoud Shojai said: "You see they allow the Prophet to be insulted. But when we talk about the Holocaust, they consider it so holy that they punish people for questioning it."
The publication of cartoons of the Prophet Muhammad sparked protests around the world earlier this year.
One showed Muhammad, whose image is banned in Islam, as a terrorist bomber.
Yad Vashem said the display in "Iran, a nation that aspires to nuclear capabilities, and whose president has made genocidal statements against Israel, is a flashing red light signalling danger not only to Israel, but to all enlightened nations".
Iran's President Mahmoud Ahmadinejad prompted international criticism last year by saying the Holocaust was a "myth" and that Israel should be "wiped off the map".