The case is getting much attention after conjoined Iranian twins died a few days ago while doctors attempted to give them separate lives.
Some medical experts had questioned the decision to actually operate on the women despite the hazards involved.
But doctors have said the age of the Egyptian twins gives them an advantage of surviving surgery.
As children, they have greater plasticity than adults, making it easier for their bones and tissue to undergo the strain of the operation and recover.
The Iranian twins were 29 years old.
Unable to walk
If they are not separated, Ahmed and Mohamed Ibrahim will likely never be able to walk because of the way their bodies are joined.
They share a band of curly hair that circles the area where their heads are fused.
The boys share large veins that drain blood out of the brain called venous sinuses.
They also share some brain material, which could be divided without causing much harm, but if their circulatory systems are not properly separated, it could kill them, doctors say.
Conjoined twins account for about one of every 2.5 million births and twins joined at the head account for about 2 percent of all conjoined births.
The parents of the Egyptian twins have said they are sure the only way to bring normalcy to their children's lives is through separation surgery.
Doctors have warned of the dangers associated with such an operation.
Dr. Kenneth Salyer, a leading facial and cranial surgeon who is treating them, said successes in these types of cases - as measured by surviving the surgery with no neurological damage - have been few.
But he said after a year of testing, planning and consultations, the medical team was confident it could be done.
Guatemalan twin girls, who are about the same age as the Egyptian boys, were separated at the skull a year ago at a hospital in Los Angeles.
The girls have suffered some setbacks, but survived their operation.