The protest grew out of anger at police's heavy-handed tactics to break up a peaceful sit-in to protect a park in Istanbul's main Taksim square yesterday.
It turned into a wider protest against Prime Minister Recep Tayyip Erdogan who is seen as becoming increasingly authoritarian and spread to other Turkish cities. Dozens were injured in the scuffles.
Today, police clashed with groups of youths trying to reach Taksim. Some threw stones at police.
The Dogan news agency says 81 demonstrators were detained in Istanbul.