The Namyldzhylakh (Russian: Намылджылах; Yakut: Намылдьылаах, romanized: Namılcılâx) is a river in Yakutia (Sakha Republic), Russia.

It is the longest tributary of the Markha, of the Lena basin.

In its middle course the river meanders strongly within a floodplain containing 90 lakes.

Finally it meets the right bank of the Markha 166 kilometres (103 mi) from its mouth in the Lena.

The river freezes in the last half of October and stays under ice until mid May.