Spanish health authorities said that they have authorized the genetic screening of pre-implantation embryos to ensure they do not carry genes that might cause cancer.
Spain's National Commission for Assisted Human Reproduction on Tuesday allowed the process for two specific cases for women undergoing fertility treatment.
One of them involved screening for a gene that causes breast cancer and other for thyroid cancer.
Any daughter born with the BRCA 1 gene has an 80 per cent risk of developing breast cancer and a 60 per cent chance of developing ovarian cancer, as well as a 50 percent risk of passing on the anomaly to their own children.
"It is an historic day in the world of health," said secretary of state for health, Jose Martinez Olmos. He said the two decisions "bring hope" for the families faced with "major health problems."
He told private radio Cadena Ser that such decisions would be made on a "case by case" basis.
The procedure is still relatively rare in the world but has been used to screen embryos for breast cancer in Britain, the United States and Belgium.
In January, a mother in Britain became the first woman in the country to have a baby selected free of a gene which causes breast cancer.
Spain's Socialist government has already angered the Roman Catholic Church with proposals to liberalize the abortion law.
In October, Catholic bishops also condemned the genetic selection of an embryo in a bid to cure a child of a crippling inherited blood disorder.