According to Phan Thuan An, a researcher of Hue's culture, variations of the Ao dai from Hue have been closely linked to historical ups and downs. Under the Minh Mang Dynasty (1820-1841), to solve the differences of clothes worn by people from different regions after the conflict of the Trinhs and the Nguyens (1623-1777), King Minh Mang issued a royal ordinance about the uniform nationwide, under which royal concubines and maids had to wear the Ao dai when they left the royal palace. Ordinary people had to wear trousers and they were prohibited to wear skirts. To adults, Ao dai was a "must" outfit.
In the early 20th century, especially since 1917 when the Dong Khanh High School for female students was established, female students were ordered to wear Ao dai as their school uniform. At present, students of Hai Ba Trung High School (old Dong Khanh School) and many other schools in Hue are encouraged to wear the white Ao dai and trousers as their school uniform.
Over the past years, although materials and designs of the Ao dai have been changed, women from Hue are loyal to their traditional Ao dai . Their thinking of the garment colours and usage remains unchanged. Besides students who wear the Ao dai at school, Hue women wear the Ao dai when they go to pagoda or during festive days which make them look both elegant and ceremonial. State female employees also like to wear the Ao dai at their offices.
Hue women choose the colour for their Ao dai to be in line with the colour of the sky and surrounding environment and the unique solemn look of the imperial city of Hue. A local saying goes, "look at the colour of the sky in order to choose the colour of the dress". The dress worn at festive days often have bright colours; at worship and ritual ceremonies they are brown, purple, blue and milky, and with hidden designs. On rainy days the dress is often dark, and on sunny days it is light and bright. Hue women like to wear the purple Ao dai, which is not too light or too dark.
The traditional Ao dai of Hue is so beautiful and romantic that it has become a topic for fashion designers to explore its beauty. Some are successful, while many fail, for the Ao dai of Hue is not something easy to renew or change. Famous designer Minh Hanh, who has many years in designing and collecting the Ao dai, said: "If someone designs a Hue Ao dai that does not reflect a Hue style, that dress is not one of Hue ." At Festival Hue 2008, Minh Hanh and other young fashion designers presented to the public a collection entitled "Imprints of the Past". The dress is designed in the old traditional style with classical designs and imprinted with a Hue style, which fully reflects the elegance and grace of Hue women.