Csík (Hungarian, in Romanian: Ciuc) was an administrative county (comitatus) of the Kingdom of Hungary.

The capital of the county was Csíkszereda (now Miercurea Ciuc).

The county was situated in the Carpathian Mountains, around the sources and upper courses of the rivers Olt and Mureș.

Most of its territory lies in the present-day Romanian county of Harghita, with small parts in Suceava, Neamț and Bacău.

In the early 20th century, the subdivisions of Csík county were: