Angry unions triggered the 24-hour general strike in protest at newly approved labor reforms and pay cuts as the crisis-hit country deals with massive unemployment and struggles to reshape its economy according to conditions set by a euro110 billion ($146 billion) international bailout.
Police kept a close watch of the demonstrations after previous ones were marred by violence -- in May, three people died in a bank torched by rioters.
A crowd including workers in overalls, immigrants and people in wheelchairs filed past shuttered shops toward the city center.
"There is huge participation in this strike ... I believe it will put pressure on the government," Stathis Anestis, deputy leader of Greece's largest union, the GSEE, told the AP.
"We want the government to take back the latest labor law that will hurt workers' rights."
Wednesday's general strike is the seventh organized this year by unions appalled at a wave of austerity policies meant to pull Greece out of its worst financial crisis since World War II.
All air, rail and ferry services have been canceled, while traffic in Athens was severely disrupted as public transport workers and taxi drivers walked off the job for hours.
Journalists are also holding a 24-hour strike, causing TV, radio and internet news blackouts, and newspapers will not be published on Thursday.
"I see that everything is horrible. Right now I am so mad," said Katiana Vrosidou, a cleaning lady waiting at a downtown bus stop. There is hardly any public transport, she noted, "and I must go to work."
Crippled by high budget deficits and a mountain of debt, Greece was saved from bankruptcy in May by an international rescue loan package. In return, the Socialists slashed pensions and salaries, hiked taxes, raised retirement ages and eased restrictions on private sector layoffs.
Late Tuesday, the government won a key vote in parliament on a fresh labor reform package that includes deeper pay cuts, salary caps and involuntary staff transfers at state companies.
The new law also reduces unions' collective bargaining powers in the private sector, where employers will be able to substantially reduce salaries.
All opposition parties opposed the reforms, which left-wing parties claim will take labor relations "back to the Middle Ages."
But Prime Minister George Papandreou's Socialists cite the need to turn around loss-making public corporations while saving private sector jobs by allowing struggling businesses to cut costs.
Unions argue that the cutbacks are unfair and counter-effective.
"These policies shift the burden of the crisis onto the backs of low salary earners and pensioners, deepen the recession and increase unemployment," the GSEE umbrella private sector union said in a statement ahead of Wednesday's strike.
Public transport workers, among those directly affected by the reforms, held a 24-hour strike Tuesday, leading to large traffic jams in Athens as commuters carpooled and used taxis to get to work.
Further transport strikes are planned for Thursday and Friday.
(Copyright 2010 by The Associated Press. All Rights Reserved.)