The Syrian Observatory for Human Rights said the IS militants died in firefights and ambushes by People's Protection Units (YPG) in eastern sectors of Kobane.
Seven YPG fighters were also killed, as well as two civilians who died in IS raids, said the Britain-based group.
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The group, which relies on a network of activists and medics on the ground for its information, said Monday the Kurdish fighters now control 80 percent of the border town.
IS launched an assault on Kobane in mid-September and came close to overrunning the town, which is also known as Ain al-Arab.
But Kurdish fighters, backed by US-led air strikes, have been able to gradually recapture territory in the small town, which is strategic because of its location on the border with Turkey.