The Nelgese (Russian: Нельгесе; Yakut: Нэльгэһэ, Nelgehe) is a river in the Republic of Sakha in Russia.

[1] The river flows across a desolate area of severe climate, with continuous permafrost.

It heads roughly north across the Yana Plateau of the Yana-Oymyakon Highlands in a wide, swampy area dotted with ancient lakes.

Then it turns northeast between the Nelgesin Range and the Tirekhtyakh Range, flowing through a narrow valley before it joins the Adycha 78 km downstream from the mouth of the Derbeke and 13 km upstream from the mouth of the Charky.

The river freezes in late September or early October and is under thick ice until the end of May.