Bangladesh Nationalist Party (BNP) Chairperson Khaleda Zia was admitted to the Evercare Hospital in the capital for a routine health check-up in the early hours of Thursday.
She left her Gulshan residence for the hospital at 1:05 am and arrived there around 2:00 am.
BNP media cell member Shairul Kabir Khan confirmed the matter.
The 78-year-old former prime minister has long been suffering from various ailments, including liver cirrhosis, arthritis, diabetes, and issues related to the kidneys, lungs, heart, and eyes.
She was released from detention on August 6, a day after Sheikh Hasina resigned as the prime minister and fled the country.