Capt. Simon Mailloux, 25, says he has unfinished business in Afghanistan. (CBC)

A Canadian soldier who lost his leg in a roadside bomb attack in Afghanistan two years ago is returning to duty to "do good."

Capt. Simon Mailloux, 25, says he has unfinished business in Afghanistan. He left the country in 2007 following an attack that severed his lower left leg and killed two other soldiers and an Afghan interpreter.

'It was already in my mind. I was meant to go, finish this mission with the boys.'—Capt. Simon Mailloux

Mailloux, a commander with the Royal 22nd Regiment at La Citadelle in Quebec City, spent two years at home healing, adjusting to his prosthesis and undergoing excruciating rehabilitation.

He said he's always known he wanted to go back to Afghanistan, from the moment he was injured. "It's never an easy decision, and it's never something that comes logically," he told CBC News.

"It's always been in my mind, from minute one. I asked my major when I was on the treatment table: 'I'll be back in a week. Just wait for me, I'll be there.'

"Of course, [I had] no idea of my wounds and how long the rehabilitation process would be, but it was already in my mind. I was meant to go, finish this mission with the boys."

Mailloux said his fiancée was surprised by his decision but expected he would opt to go back if given the choice.

"You want to do good, you want to make sure that this gonna happen well so the people [in Afghanistan] have the same chance as you," he said.

Mailloux underwent all the physical training required of soldiers heading out to mission.

He is being deployed to Afghanistan in November to serve as a staff officer at the Kandahar Airfield headquarters.

The Department of National Defence believes he is the first Canadian soldier to return to a combat zone after an amputation.