AS more than 250 Australian Defence Force (ADF) personnel were officially welcomed home from Afghanistan, Prime Minister Tony Abbott said their effort was worth it.

There are 26 girls' schools in Uruzgan province where there were previously none, he said, doctors and nurses where once there were few, and 200km of sealed roads and bridges where before none existed.

"Yes, it was worth it," Mr Abbott told the troops and their families at an official reception at Darwin's Parliament House on Saturday.

"The price was high, but the cause was great and the success has been sufficient."

Family, friends and the Darwin community were waiting to officially celebrate the ADF personnel, who returned to Australia in December following the completion of Australian operations in Uruzgan province.

Mr Abbott said that, although it was impossible to know what the future held for the people of Afghanistan, "every day you were there was better than it would have been; every day will be better than it would have been because you were there".

He was echoed by Opposition Leader Bill Shorten.

"You put yourselves at unimaginable risk ... no words that can convey the gratitude of the nation," he said.

Australia's longest war was carried out with the support of both sides of politics, said Chief of Army, Lieutenant General David Morrison.

"We are part of the ranks of men and women who have stood the lonely vigil since 1901. We are part of that great narrative of the Australian soldier - that long, lonely column stretching back across more than a century that have worn the slouch hat," he said.

"The cause was legitimate. You kept the faith. You gave all to secure Australia and to give optimism to the future security of the people of Afghanistan."

He also thanked the families of the ADF personnel for tolerating the pressure put on their home life.

"We couldn't function as a defence force without you," he said.

Forty soldiers were killed during operations in Afghanistan, and 261 were wounded.

There are 400 members remaining to provide ongoing training and advisory support for the Afghan National Security Forces.