- More than 75 million copies of Curious George books have been sold worldwide.
- Curious George has been translated into many languages, including Yiddish, Afrikaans, Braille, Japanese, French, Portuguese, Swedish, German, Chinese, Danish, and Norwegian.
- Curious George first appeared in Cecily G. and the Nine Monkeys, which was published in France in 1939. He was called Fifi in those editions.
- Hans Rey first saw his future wife, Margret, at a party in her father’s home in Germany, where she was sliding down the banister.
- When Curious George was published in 1941, King George was the king of England. So as not to be disrespectful to the king by associating him with a monkey, Curious George was called Zozo in England.
- The Reys created Curious George Goes to the Hospital at the request of officials at Boston Children’s Hospital who wanted a book to prepare children for a hospital stay. After it was published, many parents wrote to the Reys to tell them how effective the book was in reducing their child’s fear of hospitals.
- A newspaper clipping about two mice that were sent into space to study the effects of weightlessness inspired the story of George’s own space flight in Curious George Gets a Medal.
- Many of the Reys’ own interests and adventures found their way into the Curious George books. Both Hans and Margret were very fond of animals, and their first stop in a new city was always the zoo. Hans smoked a pipe; they lived among palm trees in Brazil; they rode out of Paris on bicycles; and they left Europe on an ocean liner. All of these details were woven into Curious George stories.
- The Curious George books were a true collaboration. Hans was usually in charge of the ideas and the illustrations, while Margret handled the plot and the writing.