BNP Chairperson Khaleda Zia has been taken to Bangabandhu Sheikh Mujib Medical University (BSMMU) for some medical tests.
An ambulance carrying Khaleda Zia reached the hospital around 11.30am on Saturday.
Earlier on April 1, a four-member medical board formed for the treatment of the BNP chief examined her at old central jail.
She fell sick in the jail on March 29 and postponed a scheduled meeting with its secretary general Mirza Fakhrul Islam Alamgir.
On February 8, Special Judge's Court-5 of Dhaka sentenced Khaleda to five years' rigorous imprisonment after it had found her and five others guilty in Zia orphanage trust graft case.
The court also awarded jail sentences to Tarique Rahman, now the acting chairman of BNP, and four others for 10 years and fined them Tk 2.10 crore, saying that all the six convicts have to pay the fine in equal amounts.
The Anti-Corruption Commission filed the graft case with Ramna Police Station in July 2008, accusing the six of misappropriating over Tk 2.1 crore that came from a foreign bank as grants for orphans.