Dr Karen Woo, 36, was among eight foreign aid workers executed by gunmen in an ambush in Kuran Wa Munjan district of Badakhshan province.
The Taliban claimed responsibility for the shootings. A spokesman said the team was killed because they were "preaching Christianity" and "spying for the Americans".
However, in a statement yesterday, Dr Woo's family said: "Her motivation was purely humanitarian. She was a humanist and had no religious or political agenda.
"She wanted the world to know there was more than a war going on in Afghanistan, that people were not getting their basic needs met.
"She wanted the ordinary people of Afghanistan, especially the women and children, to be able to receive healthcare.
"She undertook this trek as a medical doctor, accompanying medical supplies and to provide treatment to people who lived in an extremely remote region who had little to no healthcare available.
"Her commitment was to make whatever difference she could. She was a true hero. Whilst scared, she never let that prevent her from doing things she had to do."
Dr Woo's medical convoy was travelling through Badakhshan towards Kabul after spending three weeks in the mountainous terrain of Nuristan, where the team were delivering medical care and supplies to the people living there.
Local police said about 10 gunmen robbed the group and killed them one by one. The bodies of the aid workers and two Afghan interpreters were found on Friday next to three bullet-riddled four-wheel drive vehicles.
Foreign Secretary William Hague said: "This is a deplorable and cowardly act which is against the interests of the people of Afghanistan who depended on the services she was bravely helping to provide. Our thoughts are with her family and friends at this tragic time."
Dr Woo was working alongside Christian charity the International Assistance Mission (IAM) to set up a mother and child clinic in Nuristan.
One of the aid workers in her team was expelled by the Taliban government in August 2001 for allegedly trying to convert Afghans to Christianity.
Tom Little, an optometrist from Delmar, New York, returned to Afghanistan after the Taliban government was toppled in November 2001.
The deaths are not the first time an aid worker has been targeted in Afghanistan. In October 2008, Gayle Williams, who had dual British and South African citizenship, was killed by two gunmen on a motorcycle as she walked to work in the capital of Kabul.
In 2007, 23 South Korean aid workers from a church group were taken hostage in southern Afghanistan. Two were killed and the rest released. In 2001, eight international aid workers, including two Americans, were imprisoned and charged with preaching Christianity.
A friend of Dr Woo said she was working in Afghanistan in her capacity as a general physician – not to "convert" Muslims to Christianity.
Mark Von Koeppen, who works as a construction contractor in Kabul, said: "I can't speak on behalf of the rest of the convoy but Karen Woo was not there to convert. Her only goal was to help the people that needed help."
Dr Woo's family also paid tribute to her and said they were "so proud" of everything she had achieved.
Her fiance Paddy Smith told the BBC: "She was an extraordinary person. You don't find too many people like Karen Woo in this world unfortunately.
"Anybody that met her could not help but smile."