Gerda Weissmann-Klein was born in Bielsko, Poland. She describes her early days of life as happy and tranquil. Her parents, Julius and Helene, provided a comfortable middle class life for her and her older brother, Arthur. Gerda grew up idolizing Arthur, whom she describes as a popular and gifted student.

When Gerda was fifteen, Nazi Germany took over Poland. Shortly after the invasion began, the family received a telegram from Gerda's uncle saying that the Germans were advancing quickly and the family should leave Poland immediately. However, Gerda's father had just suffered a mild heart attack, and doctors advised that he not be moved or subjected to undue stress. Julius Weissmann ordered his children to flee Poland without him, but they refused.

When the invasion ended, Gerda and her family watched in disbelief as people whom they had considered friends began flying the Flag of Nazi Germany and using the Hitler salute. In mid-October, Arthur received a letter from the Germans. As a male between sixteen and fifty, Artur was required to register into the army. On October 18, 1939, Artur complied with the summons and never saw his family again.

Gerda and her parents were forced to live in the basement of their home and later in a Jewish ghetto. In 1942, Gerda was separated from both her parents, who were separately sent to Auschwitz, a death camp; she was sent to the Dulag (Durchgangslager, a transit camp). Later on, she was sent to labor camps in Sosnowitz, Bolkenhain, Märzdorf, Landeshut and Gruenberg; Bolkenhain being the most benign camp and Märzdorf being the worst one. In 1945, the inmates at Gerda's work camp were sent on a 350-mile death march to avoid the advance of Allied forces. The forced journey went through Dresden, Chemnitz, Zwickau, Reichenbach, Plauen, Germany on through Volary, Czech Republic and she was one of the very few who survived.

In May 1945, Gerda was liberated by forces of the United States Army in Volary, Czechoslovakia; these forces included Lieutenant Kurt Klein, who was born in Germany and immigrated to the United States to escape Nazism. Both of his parents had been murdered by the Nazis at Auschwitz. The two fell in love and became engaged in September 1945.

In 1946, Gerda and Kurt Klein were married in Paris. They settled in Buffalo, New York and had three children. She became involved with local charities and later began to speak about her experiences during the war. In 1998, the Kleins started the Gerda and Kurt Klein Foundation, which promotes tolerance, respect, and empowerment of students through education and community service. Kurt Klein died in 2002, but Gerda remains active in the foundation and regularly speaks about her experiences during the Holocaust. She is represented by Leading Authorities speakers bureau. On January 27, 2006, she spoke to the United Nations as part of the International Day of Commemoration in memory of Holocaust victims.She wrote a memoir entitled All but My Life.

Books by Gerda Weissmann Klein include:

• All But My Life (1957)
• The Hours After: Letters of Love and Longing in War's Aftermath (2001, co-written with Kurt Klein)
• A Boring Evening At Home
• The Promise of a New Spring
• A Passion for Sharing: The Life of Edith Rosenwald Stern (1984)
• The Blue Rose (1974)
• Peregrinations: Adventures with the Green Parrot (1986)
• The Wings of Epoh