Jorge Videla, former Argentine president, has been sentenced to 50 years for "systematically" stealing the babies of prisoners.
Thursday's verdict finds Videla, 86, guilty of kidnapping hundreds of babies from leftist activists detained and killed between 1976-1983.
"We have presented evidence showing that the kidnappers plotted to steal the children born to women in captivity," Estela de Carlotto, president of the Grandmothers of Plaza de Mayo, told the AFP news agency.
The rights group has fought in court since 1996, demanding restitution for the children stolen while their mothers were held in clandestine detention.
The group says in total some 500 children were kidnapped and then raised as their own by families close to the regime.
The case, which Al Jazeera's Teresa Bo, reporting from Buenos Aires, says shocked Argentine society, also included doctors accused of involvement in the kindappings.
Our correspondent said that the defence's request that Videla be allowed to serve his sentence under house arrest, due to his advanced age, was denied.
Videla defended his actions last week, saying in court that the children's mothers were "terrorists".
"All those who gave birth, who I respect as mothers, were active militants in the machinery of terrorism. They used their children as human shields," said the former general, who has already been sentenced to life in prison for crimes against humanity.
Elliott Abrams, a former US department of state assistant secretary for human rights, said in January, that the United States, an ally of the Videla government, was aware of a systematic practice of stealing children.
"We believed there was a plan, because they were arresting or assassinating a lot of people, and we got the impression that the military government had decided that at least some of the children of those people would be given to other families," he testified from the Argentine consulate in Washington.
"We knew that certain children had been given away while their parents were in prison or deceased," Abrams said. "They took them and gave them away".
