resident Barack Obama has been briefly heckled as he addressed students at the largest US Catholic university, amid a row over abortion rights.
Anti-abortion activists have protested against the president's visit to Notre Dame, in Indiana.
Protests and vigils have been held on and around campus, with several people arrested before Mr Obama's speech.
Mr Obama, who received an honorary degree, defended the right to abortion but said the procedure should be rare.
After entering the White House in January the president also quickly moved to reverse a Bush-era ban on embryonic stem-cell research, angering many social conservatives.