Received December 19, 2019
Accepted June 20, 2020

In March 2019 Japan modified its norms regarding research with human/non-human chimeras. The amended rules allow the creation of chimeras with human brain cells, and the subsequent transfer of the resulting creature to a uterus, where it can develop for more than 14 days, eventually until term. At this moment, it is still uncertain the real consequences of this new regulation in actual research. But many concerning issues have already been identified. This paper will start by addressing traditional topics involving this practice: the use of non- human animals in research, the use of human stem cells in scientific experimentation and the creation of human/non-human chimeras. Subsequently, it will analyze the new concerning issues brought by the amendment of 2019: the use of human brain cells, the transference of the chimera to a uterus and its development for more than 14 days, and the possibility of using animals which present close similarities with humans. In the end, the paper will conclude that in spite of the legal and ethical hazards that this new regulation might carry, it should be allowed under strict scrutiny.