A team of 50 specialists in Spain has separated Moroccan-born Siamese twins.
The operation on the 21-month-old girls took eight hours.
Fatima and Amina Agunin were joined at the lower back, and shared two legs and the same genital and urinary system.
Doctors at La Paz hospital in Madrid say the operation appears to be a total success but stress that there is still considerable work to do before it is complete
A hospital spokesman said the operation had not been excessively life threatening as the twins did not share any vital organs.
The twins are left with a leg and a kidney each.