A parole board has decided against freeing a Thomas Edwin Blanton Jr, 76.
The decision was met with applause at the hearing in Montgomery and relatives of the girls killed spoke against Blanton's release during the hearing.
Blanton is the last surviving KKK member convicted of murder over the bombing of Birmingham's 16th Street Baptist Church.
It killed four girls; 11-year-old Denise McNair and 14-year-olds Addie Mae Collins, Carole Robertson and Cynthia Morris, also known as Cynthia Wesley.
They were inside the church preparing for worship that Sunday and died instantly.
One child survived but was seriously injured, Addie Mae's sister, Sarah Collins Rudolph.
Their deaths inside a church on a Sunday morning became a symbol worldwide of the depth of racial hatred in America's segregated South.
Blanton was convicted of murder and sentenced to life imprisonment in 2001 for being part of a group of KKK members who planted a dynamite bomb that exploded outside the church on September 15th 1963.
The bomb was planted at a time when Birmingham's public schools were facing a court order to desegregate, so that white and black pupils were able to learn in the same schools side-by-side.
Two others were convicted; Robert Chambliss, convicted in 1977, and Bobby Frank Cherry, who was convicted over the bombing in 2002.
They both died in prison.
The KKK maintains an ideology of white supremacy and an anti-immigration sentiment.
Blanton can be considered for parole again in five years.
