Patty Duke, who won an Oscar as young Helen Keller in the 1962 version, played Anne Sullivan in the 1979 TV version and won an Emmy for it.
Melissa Gilbert originally wanted to offer the part of Annie Sullivan to Meredith Baxter, but the adults working on the project suggested offering the part to Patty Duke, who had played Helen Keller in The Miracle Worker (1962).
The original Broadway production of "The Miracle Worker" opened at the Playhouse Theater on October 19, 1959, ran for 719 performances, and won the 1960 Tony Award for Best Play. Anne Bancroft (winner of the 1960 Tony Award for Best Actress in a Play) and Patty Duke recreated their stage roles in the movie. William Gibson wrote the teleplay, the stage play and the screenplay.
British actress, Lynne Frederick, expressed interest in playing Annie Sullivan, but the producers considered her to be too beautiful and young for the part. Ironically, Frederick (aged 25) was only five years older than the real Anne Sullivan was when she first came into Helen's life (aged 20).
Melissa Gilbert has admitted that she was miscast to portray Helen. "I was almost exactly the same height as Patty Duke, too tall.'