Humpty Doo is a small town in Australia's Northern Territory. It is situated just south of the Arnhem Highway, approximately 40 km from Darwin. At the 2006 census, Humpty Doo had a population of 5,413.
The town is known for agriculture experiments that have occurred there. In 1954, after some experimentation by CSIRO, a joint Australia-U.S. company called Territory Rice Ltd. was formed with a plan to irrigate the subcoastal plain of the Adelaide River in order to commercially produce rice. The plan was a complete failure due to several factors, including an invasion of geese, soil that was too saline and an insufficient amount of drainage, all combined with poor management. They gave up the land to the government in 1962. The Rice Project was 20 km east of the present town on part of the Humpty Doo Station where the name "Humpty Doo" was first used. The irrigation dam, called Fogg Dam, is still there and an attraction for bird watching.
A more successful agricultural experiment was the growing of mangos. Top quality fruit from Humpty Doo is picked earlier than Queensland mangos and fetches a top price in southern markets. There is a honey farm located in outer Humpty Doo, Humpty Doo Apiaries.