Nuns of Missionaries of Charity, the Catholic Order founded by Mother Teresa to help the poorest of the poor, the infirm and the dying, held special prayers at their global headquarters Mother House.
Devotees thronged the central Kolkata building since dawn to offer floral tributes and prayers at Mother Teresa's grave.
People from rural areas were seen kneeling before the grave with candles in hand as they sang hymns in memory of Mother Teresa, who died Sep 5, 1997.
Programmes in Mother Teresa's memory were held in schools across the city.
Mother Teresa, born Agnes Gonxha Bojaxhiu in Skopje, Macedonia on August 26, 1910, to an ethnic Albanian family, made Kolkata her home and workplace for 68 years since 1929.
She was given the Nobel Peace Prize in 1979. Her work, dedicated to the poor and the diseased, inspired many.