Pope John Paul II urged scientists to use their research to help poor countries not to make a profit.
The 82-year-old pontiff expressed gratitude on Monday for those working in biomedicine for improving quality of life. But he said research must follow "an authentically humanist orientation" and keep itself "free from the slavery of political and economic interests."
The pope said there was growing urgency to fill the "unacceptable gap that separates the developing world from the developed world" in advances in biomedical research, "to support the populations afflicted by misery and by disastrous epidemic. I am thinking in a special way of the drama of AIDS, especially grave in many countries of Africa."
There has been outcry in recent years over the inability of poor people to afford AIDS medicines that can ease symptoms or prolong survival.
The pontiff also called for ethical research which avoids "every temptation to manipulate man."
The Vatican opposes human cloning along with fertility treatments that violate Roman Catholic teaching, which holds that conception should only be achieved through intercourse by a married couple.