The senior leaders paid floral tributes at Vir Bhumi, the samadhi of Rajiv Gandhi.
Rajiv's wife and Congress president Sonia Gandhi, daughter Priyanka Vadra and her husband Robert Vadra, also laid flowers at the samadhi on the occasion.
Rajiv's son and Congress General Secretary Rahul Gandhi was not seen at the memorial during the prayer programme.
Defence Minister AK Antony, Lok Sabha Speaker Meira Kumar, Deputy Chairman Planning Commission Montek Singh Ahluwalia, Minister of State in the Prime Minister's Office, V Narayanswamy, were among the other leaders who paid floral tributes at the samadhi.
School children, clad in white dress, later marched towards the samadhi with a Tricolour to showcase a performance depicting communal harmony. Classical devotional music was being played throughout the programme.
Rajiv Gandhi, who heralded the information and communication technology revolution in the country, was born on Aug 20, 1944 and served as the sixth Prime Minister of India from 1984-1989. He was assassinated by the LTTE on May 21, 1991 at Sriperumbudur in Kanchipuram district of Tamil Nadu while addressing an election campaign.