The Greek unemployment rate climbed to 27.6 percent of the workforce in May from 23.8 percent in May last year, the state statistics agency said Thursday.
The agency noted that over 171,000 people had lost their jobs in the intervening year, including over 22,000 in May.
Overall, more than 1.38 million Greeks were officially registered as unemployed, while 3.6 million people had jobs.
A breakdown of the data showed that women were more likely to be unemployed, at a rate of 31.6 percent compared with 24.6 percent among men.
The highest rate was registered for youth aged 15-24, at 64.9 percent.
The heavily-indebted country has been in recession since 2008, with unemployment continuously on the rise.
Dependent on international loans for its economic survival, Greece has had to accept deep austerity measures in exchange for financial aid from the European Union and the International Monetary Fund.
In a recent report, the IMF noted that Greek economy was "rebalancing" through recession, having lost 25 percent in output since a 2007 peak.