Up to 40 people are protesting outside the first private clinic to offer abortions in Northern Ireland.
The service, run by Marie Stopes, opened in Belfast on Thursday.
It has said it will provide terminations within NI's current legal framework - abortions are not illegal but are very strictly controlled.
The protesters at the clinic are from a range of religious denominations and are holding up placards with images of aborted foetuses.
An anti-abortion group has called for the clinic to be shut down, but Abortion Rights welcomed its opening.
Northern Ireland, unlike the rest of the UK, is not covered by an Abortion Act.
Abortions can be carried out only to preserve the life of the mother or if continuing the pregnancy would have other serious, permanent physical or mental health effects.
There is strict assessment regarding any impact on mental well-being and the woman must consult with two clinicians.
The Marie Stopes clinic has said it will carry out medical, not surgical, procedures only up to nine weeks gestation and only within the existing legal framework.
It said that the health professionals in the clinic will be from Northern Ireland and that they will make the assessments, although the views of the woman's own GP will be taken into consideration.
The clinic's services will also be available to women from the Republic of Ireland, if they meet the legal criteria in Northern Ireland.
The strict rules on abortion in Northern Ireland do not prevent women from travelling to the rest of the UK for the procedure.
A 24-week limit for abortion applies in England, Wales and Scotland, where abortions are allowed under certain conditions, including that continuing with the pregnancy would involve a greater risk to the physical or mental health of the woman, or her existing children, than having a termination.
The permission of two doctors - or one in an emergency - is also needed.
Abortions after 24 weeks are allowed in Britain but only in extreme circumstances - if there is grave risk to the life of the woman, evidence of severe foetal abnormality, or risk of grave physical and mental injury to the woman.