Cymru oedd y wlad gyntaf yn y DU i newid y system rhoi organau drwy gyflwyno system feddal o optio allan. Caiff pobl 18 oed neu hŷn sydd wedi byw yng Nghymru am fwy na deuddeng mis ac sy'n marw yng Nghymru eu hystyried bellach fel pe baent wedi rhoi cydsyniad i roi organau, oni bai eu bod wedi optio allan. Mae hyn yn cael ei alw'n gydsyniad tybiedig.
Wales became the first part of the UK to change the organ donation system when it introduced a soft opt-out system. People aged 18 and over who have lived in Wales for more than 12 months and who die in Wales will now be regarded as having consented to organ donation unless they have opted opt. This is called deemed consent.