The Trans-Alay or Trans-Alai Range (Kyrgyz: Чоң Алай кырка тоосу, Chong Alay kyrka toosu; Tajik: қаторкӯҳи Паси Олой, qatorkŭhi Pasi Oloy, or қаторкӯҳи Каюмарс, qatorkŭhi Kayumars; Russian: Заалайский хребет, Zaalaisky Khrebet) is the northernmost range of the Pamir Mountain System.

Following the collapse of the Soviet Union, the range has been divided between Tajikistan and Kyrgyzstan.

The name was from the viewpoint of Russian explorers in the region: The Alay Range lies to the north of the Alay Valley, formed by the Kyzyl-Suu or upper Vakhsh River, one of the principal tributaries of the Amu Darya.

The range on the far side of the valley, more distant from Russia and its outposts, became known as the Trans-Alay.

The southern valley dividing the Trans-Alay from the Pamir proper is that of the river Muksu.