The Swedish branch of the charity later said that the five were from Belgium, Denmark, Peru, Sweden and Switzerland.
MSF said that the kidnapping took place on January 2 in a hospital that it was running in northwestern Syria to provide essential healthcare to people affected by the country's raging civil war.
In the wake of the abduction, MSF said it was forced to close one hospital and two health centres in the Jabal Akrad region.
"The relief of seeing our colleagues return safely is mixed with anger in the face of this cynical act that has cut off an already war-ravaged population from desperately needed assistance," MSF's president Joanne Liu said in a statement.
"The direct consequence of taking humanitarian staff is a reduction in lifesaving aid. The long-term victims of this abduction are the Syrian population. Some 150,000 people in the Jabal Akrad region are now deprived of MSF's medical care, while living in a war zone."
In 2013, MSF medical staff in the three now-shuttered facilities performed 521 surgical operations, many for trauma wounds, more than 36,000 medical consultations, and safe hospital deliveries for more than 400 mothers, the organisation said.
"Across northern Syria, where MSF continues to operate other medical facilities, security constraints have made it extremely challenging to provide assistance," it said.
- 'Complete disregard' -
MSF said that medical facilities had been attacked and bombed, and health workers killed or threatened by armed groups.
Elsewhere in Syria, denial of official access and insecurity have prevented MSF from being able to set up medical activities, the organisation said.
It said the kidnapping was a stark illustration of the brutality seen in the Syrian war, which has driven millions of people from their homes and claimed more than 150,000 lives.
"This incident is representative of the complete disregard shown toward civilians throughout Syria today," said Liu.
"While millions of Syrians need assistance for their survival, among some of the armed parties to the war, the very idea of independent humanitarian presence is rejected," she added.
Given the massive needs of Syria's embattled population, Lui said that MSF should be running some of the largest medical programmes in the organisation's four-decade history.
"In the current environment our capacity to respond is painfully limited," she said.
MSF has been running makeshift hospitals and health centres across the north of Syria since 2012, a year after the war broke out following a crackdown on protests against the regime of President Bashar al-Assad.
In addition, it is helping a network of Syrian medical groups run 50 hospitals and 80 health centres, as well as running programmes for some of the over 2.7 million refugees who have fled to Iraq, Jordan and Lebanon.