The leader of the influential Cuban protest group, Ladies in White, has died in the capital, Havana.
Laura Pollan, who was 63 years old, had been in hospital for a week suffering from Dengue fever.
She founded the group 10 years ago when her husband was jailed.
The group's members, dressed in white, gathered in central Havana at the weekends to demand freedom for a group of 75 men imprisoned during government repression in 2003.
After being hospitalised, Pollan developed severe respiratory problems.
Her daughter, Laura Labrada, said she had had a tracheotomy.
Initially composed of family members of those dissidents, the group later championed wider human rights issues, and continued to campaign for the release of all political prisoners in Cuba, even after all 75 were freed.
Laura Pollan's husband, Hector Maseda, was among the last of the 75 to be freed in February this year.
"As long as this government is around there will be prisoners," she said in the interview with the Associated Press. "Because while they've let some go, they've put others in jail. It is a never-ending story."
In 2005, the group was awarded the Sakharov prize by the European Parliament.
And earlier this year, the Ladies in White received the US government's Human Rights Defender Award for what Washington called their exceptional valour in protecting human rights in the face of government repression.
Ladies in White have often faced harassment from groups of government supporters.
The communist authorities say such demonstrations are spontaneous reactions by ordinary Cubans, but the opposition say they are orchestrated by the government.