Istanbul's gay pride march had been banned again this year - over concern for public order - but dozens of marchers came out anyway.
They were met by Turkish police with tear gas and rubber pellets.
Some 19 people were detained and a German member of parliament says two of his colleagues were among them.
German MP Volker Beck:
(SOUNDBITE) (English) GERMAN MEMBER OF PARLIAMENT, VOLKER BECK, SAYING:
"I have no idea why two persons of our delegation, two young German guys, were captured. They did nothing else than everybody, standing just under the Turkish heaven."
Turkish activists have been holding the Istanbul gay pride march since 2003, and it went on largely uninterrupted every year until last year.
This year, an ultra-nationalist youth group had threatened violence if the march pressed on, saying the event is 'immoral'.
Unlike many other Muslim countries, homosexuality isn't a crime in Turkey.
But homophobia remains widespread -- and critics of President Tayyip Erdogan say his party has been intolerant of dissent.