Hungarian civil organisations protested against a new law that Budapest says cracks down on paedophilia and critics argue is an attack on the LGBT community.
In Budapest, protesters set up a 10-metre tall heart balloon in the colours of the rainbow. The EU has also expressed outrage over the law.
Introduced by Prime Minister Viktor Orban's ruling Fidesz party, the new law was originally aimed at toughening punishments for child abuse.
But late modifications included a ban on the "display or promotion" of homosexuality and gender reassignment to under-18s, as well as restrictions on sex education in schools.
Andrea Sztraka, an activist from Amnesty International Hungary, was defiant: “You don't have to be silent, you don't have to be afraid. We launched a petition today calling on the Ombudsman to send the law to the Constitutional Court for a veto. Anyone can sign it.”
Hate crimes have increased significantly in Hungary since the ratification of the new law, and at least two homosexual couples have been attacked.
A homophobic group has written a list of the Pride events they plan to disrupt, although so far they have not been seen in attendance.