Jailed November 17 terrorist Dimitris Koufodinas, who had gone on a hunger strike for almost two weeks, was released from the Nikaia state hospital on Monday.
He was to be returned to Korydallos maximum security prison before he is granted his third 48-hour furlough.
Koufodinas, who is serving 11 life sentences for his role in the N17 terrorist group, went on a hunger strike on May 30 because authorities refused to give him a leave of absence from prison. He was transferred to hospital earlier in the month.
Before authorities agreed to grant him furlough, anarchist and anti-establishment groups launched a series of attacks against targets across the country, including the offices of the Hellenic American Union (HAU) in Athens and Thessaloniki.