The rights organization says Jaffar Maki and Mohamed Ali were convicted of taking part in unsanctioned demonstrations in early 2011. Pro-democracy groups at the height the so-called Arab Spring protested against the Sunni-led monarchy in Bahrain.
Human rights groups have criticized the monarchy for its crackdown on the opposition. Human Rights Watch said both men need urgent medical care for injuries suffered at the hands of security forces during the uprising.
"These young men have already paid a heavy personal price and deserve an end to this nightmare," said Sarah Leah Whitson, Middle East director at Human Right Watch, in a statement from Beirut.
Both men were injured by gunfire.
Early this week, the rights group called for disciplinary action against authorities suspected of endangering civilian lives when responding to a protest led by the opposition al-Wefaq party in Bahrain.
Bahrain had pledged to consider a series of reforms recommended last year by an independent commission examining the violence.