The film is partially autobiographical. When Hayao Miyazaki and his brothers were children, his mother suffered from spinal tuberculosis for nine years and spent much of her time hospitalized. It is implied, yet never revealed in the film, that Satsuki and Mei's mother also suffers from tuberculosis, as she was hospitalized in a sanatorium (a specialized hospital for tuberculosis patients and usually located in the countryside), which caused the whole family to move to the countryside. He once said the film would have been too painful for him to make if the two protagonists were boys instead of girls.
The names of the two girls, Satsuki and Mei, are words similar to the month of May. "Satsuki" is an old Japanese word for May, and "Mei" is the Japanese pronunciation of the English word "May".
The forest creatures and title characters of this movie got their name when Mei, the little girl who first sees them in the film, mispronounces the word "troll." At one point in the original Japanese language version, when Satsuki first finds Mei sleeping in the grove behind their house, Mei tells her sister she saw a "Totoro". Satsuki replies, "Totoro, do you mean troll, from the storybook?" and Mei nods in agreement. This aspect of the story was left out of the 1993 Fox English version, probably because the difference between "to-ro-ru" (the Japanese pronunciation of "troll") and "to-to-ro" would have been lost on English-speaking audiences. The quote is included in the 2006 Disney English version.
The movie initially did not do well at the box office and did not break even until about two years after the release when stuffed dolls based on the King Totoro character hit the shelves.
On its original theatrical release in Japan, it was double-featured with Grave of the Fireflies (1988), as the film was believed to be too big a financial risk as a standalone release.