RU486 suppresses the body's production of progesterone
The sale of the abortion pill RU486 has been given final approval in Italy, despite protests from the Vatican and the government in the Catholic country.
Unlike in other European countries, the pill, also known as mifepristone, will be administered solely in hospitals.
The pill was originally approved by the country's pharmaceuticals agency in late July, but the move prompted a parliamentary inquiry.
Italy was is one of the last European states to make it available.
According to the country's pharmaceutical agency, the pill must only be administered in a hospital environment and must be taken within seven weeks of conception.
Women will be required to remain in hospital until the drug has taken full effect.
"The debate is not yet over," Senator Donatella Poretti told Agence France Presse.
"From tomorrow, we have to ask why Italian women [prescribed the drug] will be required to stay in hospital."
The introduction of the pill had sparked outrage from the Vatican.
Bishop Elio Sgreccia, vice-president of the Pontifical Academy for Life, had threatened women who used it, doctors who prescribed it and those who encouraged its use with excommunication.
RU486 was first introduced in France two decades ago and is available in the US and several other European countries.
It allows the patient to have a chemically induced abortion instead of a surgical procedure within the first seven weeks.
The pill suppresses the body's production of a hormone called progesterone, causing the uterine lining to thin and reject an implanted embryo. There have been some concerns over its side-effects, which include heavy bleeding and nausea.
Italian law permits surgical abortion on demand in the first 12 weeks of pregnancy, and then until the 24th week only if the foetus has a genetic deficiency or to preserve the mother's health.