One soldier was also injured in the fighting on Sunday night in the Mazgirt and Nazimiye districts of mountainous Tunceli province, said military officials on Monday.
One woman was among the five dead fighters from the separatist Kurdistan Workers Party (PKK).
An official said 4,000 soldiers were taking part in the operation, supported by helicopters. It began after around 25 fighters were located in the region.
He said explosives were seized during the operation.
Violence has increased in the mainly Kurdish southeast since the PKK ended a unilateral six-year ceasefire on 1 June.
Security officials estimate more than 2,000 separatists have entered Turkey in recent months from hideouts in northern Iraq.
One soldier was killed and another injured on Saturday when their vehicle ran over a landmine planted by dissidents in the southeast.
The PKK launched an armed campaign for an ethnic homeland in the southeast in 1984 and more than 30,000 have been killed in the fighting. A ceasefire was declared in 1998. PKK leader Abd Allah Ocalan was captured the following year.