Kashmir has been divided between India and Pakistan for six decades, and the fortnightly bus service that began this month is seen as a key confidence-building step towards peace between the nuclear rivals.
But groups seeking Kashmir's independence or incorporation into Pakistan oppose the buses and have threatened to attack them.
Three buses - two from India, one from Pakistan - departed on Thursday morning in opposite directions from Srinagar and Muzaffarabad, the capitals of the Indian- and Pakistani- administered portions of Kashmir.
Mohammed Tayab, a Pakistani government official, said 38 passengers travelled from India and 25 from Pakistan.
There was little of the fanfare of the 7 April inauguration. The departure from Srinagar was kept under wraps until the
Thousands of security officers were deployed along the 120km road to the Line of Control that divides Kashmir.
Separatist groups attacked the
first batch of passengers
The buses were accompanied by an ambulance and several armored vehicles.
Security was also tight on the Pakistani side, although there's little threat of attack there. Later, the Indian passengers safely reached Muzaffarabad to meet with their relatives and friends.
At the border, the passengers crossed a white steel bridge on foot while Pakistani and Indian soldiers raised white flags at either end before opening the gates. The passengers swapped buses to continue their journey.
"I don't care about threats. I am going to see my relatives without any fear or danger," Shahzadi Begum, 50, said before she left from Muzaffarabad, a trip her son took on the first bus two weeks ago.
Begum last visited India's part of Kashmir 20 years ago.
"I don't care about threats. I am going to see my relatives without any fear or danger"
Shahzadi Begum, 50
Khalid Mahmud, 60, who was returning to India after coming to Pakistan on the first bus, said he had met cousins and four uncles on his trip.
Mahmud said: "People gave us love here. I am going back with good memories from here."
Muhammad Abd Allah Bhat, 75, who returned from Muzaffarabad along with his wife after seeing his daughter and grandchildren there, said "it was the best journey of my life".
"We met the kids after 16 long years. Thank God I lived to see this day. We salute General Musharraf and Manmohan Singh for making it possible."
Passengers from Pakistan were also jubilant. Raja Altaf, who lives in Pakistan's part of Kashmir, said he left Indian Kashmir in 1965. "When I was crossing the bridge I felt that I will go mad with joy. I can't explain the how it feels to return to one's homeland," he said.
Last week, four armed separatist groups warned that passengers "who are planning to ride on the second Srinagar-Muzaffarabad bus should stand warned and not put themselves in danger".
The same groups had threatened to disrupt the first bus and carried out an attack on the heavily guarded complex in Srinagar where passengers were staying.
Passengers have so far ignored
threats of attacks by separatists
Most of the region's armed groups see the bus service as a gimmick that gets them no closer to their separatist goals.
More than a dozen Pakistan-based rebel groups have been fighting for Indian-administered Kashmir's independence or its merger with Pakistan. At least 66,000 people, mostly civilians, have been killed in the conflict since 1989.
Thousands of families have been divided by the conflict in Kashmir, the cause of two of the three wars between Pakistan and India since independence.
"We met the kids after 16 long years. Thank God I lived to see this day"
Muhammad Abd Allah Bhat
Over the weekend, Pakistan's president, Gen. Pervez Musharraf, and Indian Prime Minister Manmohan Singh met in New Delhi and declared the peace process begun a year and a half ago was "irreversible", although there's no immediate sign of a settlement to the Kashmir dispute.
Meanwhile, in the southern Pakistani city of Karachi, senior border security officials from Pakistan and India began four days of talks Thursday on fighting drug smuggling, illegal border crossing and repatriation of people who inadvertently cross the frontier between southeastern Pakistan and western India.