'sub-district' pronounced: ['upɘdʒeːlaː]), formerly called thana, is an administrative division in Bangladesh, functioning as a sub-unit of a district.

The administrative structure consists of divisions (8), districts (64), upazilas (495) and union parishads (UPs).

This system of devolution was introduced by the former military ruler and president of Bangladesh, Lt-Gen Hossain Muhammad Ershad, in an attempt to strengthen local government.

Below UPs, villages (gram) and para exist, but these have no administrative power and elected members.

The Local Government Ordinance of 1982 was amended a year later, redesignating and upgrading the existing thanas as upazilas.

UNOs are senior assistant secretary of Bangladesh Civil Service (Administration) Cadre.