One of the conjoined adult Iranian twins separated after unprecedented surgery has died, CNN reported, citing officials at Singapore's Raffles Hospital.
Ladan died due to a loss of blood as the separation of the twins' brains was coming to a close.
The condition of her sister Laleh is still critical.
The 29-year-old sisters, both law graduates, said they were willing to accept the risks and face those dangers to lead separate lives.
The operation is a landmark procedure. Although Singapore doctors performed a similar operation in 2001 on infant Nepalese girls, surgery on adult twins is unprecedented.