Clashing perspectives on the ethics of the donation of human eggs for research purposes are likely to complicate international collaboration whether stem-cell researchers like it or not.

The international AIDS meeting still has a purpose.

A Nature Special Report investigates the ethics and economics of donating eggs for stem-cell research. In this, the first part Erika Check investigates whether paying donors would increase supply. In the second part Helen Pearson asks what is known about the long-term health risks faced by donors.