On November 25, 2001, researchers at a private biotechnology company called Advanced Cell Technology announced that they had successfully cloned human embryos. The scientists reported the results of two different methods of producing human clones.

In the first method, they began with a donated human egg cell. They carefully removed the cell's nucleus, and then replaced it with a cumulus cell, which is a human cell that develops in the ovary with egg cells and supports the growth of those egg cells. Cumulus cells are small enough that they can be injected whole into the donor eggs. The scientists used 71 eggs from seven volunteers to create a single cloned early embryo. Of the eggs injected with cumulus cells, two made it to the four-cell embryo stage, and one progressed to six cells, before its growth stopped.

The second method the scientists employed is called parthenogenesis. In these studies, they exposed 22 eggs to chemicals that changed the eggs' internal environment. Six of the eggs developed into what appeared to be blastocysts, early embryos, but none progressed to develop the inner cell mass that yields stem cells.

The researchers said that their studies were intended to be used for therapeutic cloning, the creation of specific cell lines in the service of fighting particular diseases or conditions. For example, they could collect eggs from a woman with heart disease or diabetes. They would produce blastocysts from her eggs and then use appropriate growth factors and chemicals to induce those blastocysts to produce the heart muscle or insulin cells that the patient needed, and then inject those healthy cells back into her. Because they came from her own body, the woman would not be likely to suffer rejection of those cells. This is not as easy to accomplish for a man, but, theoretically, if two of his sperm cell nuclei were injected into a donor egg, a blastocyst might develop. Two sperm would be needed because eggs and sperm contain only half the necessary genetic material.

The response to the announcement by Advanced Cell Technology was varied, but generally negative.

President George W. Bush condemned it, stating, "The use of embryos to clone is wrong. We should not as a society grow life to destroy it. And that's exactly what's taking place." He urged the Senate to act on legislation already passed by the House of Representatives to ban human cloning for any purposes. Senator Sam Brownback of Kansas stated that he would introduce legislation to call for a six-month moratorium on cloning research in order to permit more study. Senate Majority leader Tom Daschle suggested that he would prefer not to rush legislation through the Senate so that Senators could have time to understand the implications of the research. The Vatican and the National Right to Life committee both condemned the research.

Many in the scientific field expressed some skepticism over the reported results. Indeed, the study was published in a non-peer reviewed format. Although most will acknowledge that this a provocative first step towards generating cloned human embryos that may provide useful stem cells, the current study in no way demonstrated this utility. The embryos produced did not reach the stage that would permit growth of stem cells. Indeed, generating "cloned" embryos that containing DNA from a somatic cell is not that difficult. Getting them to a stage where they provide useful stem cells is likely to be much harder. Because of this, many scientists believe that the report by ACT was done more for publicity then for the advancement of science or medicine.