A 10-day strike by metro workers in Athens ended on Friday after the Greek government threatened them with arrest unless they returned to work.
Although a protest by some public transport workers continued, the metro reopened at around 3pm.
Police earlier stormed a metro depot in the city, breaking up a sit-in. Traffic was gridlocked as commuters struggled to work by car.
Athens is trying to implement austerity measures unpopular with trade unions.
The BBC reports the strike had crippled the underground system. The Athens metro, trams and suburban railway serves more than 1.1 million passengers daily.
A civil mobilisation order issued by the government on Thursday threatened metro workers with dismissal, arrest and even imprisonment.
It was the first time the coalition had invoked a 2007 emergency law to deal with "peace-time emergencies".
Such legislation has only been used nine times since the collapse of a military dictatorship in 1974.