The Britain-based Syrian Observatory for Human Rights and local activist Mohammed Saeed say troops recaptured Douma outside the capital late Friday.
The Observatory says conditions in Douma are miserable, with dead bodies in the streets.
It says there is a lack of food, electricity and running water.
Douma has been a hotbed of dissent since the uprising against President Bashar Assad began in March last year.
Troops loyal to Assad are strong in central Damascus, but have battled to control the ring of suburbs and settlements in the surrounding countryside. The army launches frequent offensives into the suburbs only to see them slip back into rebel control.