A second medical evacuation flight carrying 24 critically ill Yemenis left the rebel-held capital Sanaa on Saturday, the World Health Organisation said.
"The flight just took off from Sanaa headed to Amman," a WHO spokesperson told AFP.
The plane was carrying men, women and children in need of medical treatment, along with their companions, the spokesperson added.
The flight had been due to leave Sanaa on Friday but was rescheduled for "technical reasons," according to the WHO.
A first "mercy flight" evacuated seven children from Sanaa on Monday for medical treatment in Jordan.
The United Nations is eager to build the necessary confidence between the warring parties in Yemen to enable more such evacuations.
The WHO said Friday it was " committed and working very hard to ensure these Yemeni patients receive the treatment they need."