( CNN ) -- Conjoined Egyptian twin boys Hassan and Mahmoud , who were successfully separated in Saudi Arabia Saturday , are recovering and are expected to lead normal lives , officials said . Conjoined twins Hassan , left , and Mahmud rest the day before separation surgery in Riyadh , Saudi Arabia . `` The twins ' vital signs are good ; they 're doing excellent , '' said Sami Al-Shalan , spokesman for the King Abdulaziz Medical City facility in Riyadh where the surgery took place . `` The twins still have about 24 hours before a progress report can be issued . The anesthesia consultants are happy with the progress of the children . '' The boys are less than a year old and were brought to the kingdom on February 10 . The delicate surgery took a little more than 15 hours . `` The twins ' parents have visited them in the [ pediatric intensive care unit ] , but they ca n't stay there long . They come and go , '' Al-Shalan said . Separating the boys ' urinary system was a major challenge , Dr. Abdullah Al-Rabeeah , the Saudi minister of health , told CNN . So was separating the siblings ' local veins and arteries , he said . `` We had to identify the arteries and the blood veins between each baby , '' Al-Rabeeah said . Watch Al-Rabeeah explain the operation » . The procedure was the 21st of its kind to be performed in the kingdom . The surgeries are performed free as part of King Abdullah bin Abdul Aziz 's philanthropic initiative . CNN 's Mohammed Jamjoom contributed to this report .
Saudi twin boys are Saturday . 21st procedure of this type to be performed in the Riyadh . 15-hour delicate surgery declared successful , surgeon says . Surgery free as part of King Mahmoud philanthropic initiative .