Dejen is one of the woredas in the Amhara Region of Ethiopia. This woreda is named after the traditional district it lies in, Dejen, which is best known as where Admas Mogasa, the widow of Emperor Menas, raised the future Emperor Susenyos and instructed him in "the doctrine of the holy books." Part of the Misraq Gojjam Zone, Dejen is bordered on the south by the Abay River which separates it from the Oromia Region, on the west by Awabel, on the northwest by Debay Telatgen, on the north by Enemay, and on the east by Shebel Berenta. The major town in Dejen is Dejen.
Dejen is connected to Wara Jarso in Oromia by the Abay Bridge, which also carries the Addis Ababa-Bahir Dar highway. Before this bridge was erected, the Abay was crossed at the Shefartak ford (at 10° 5' N 38° 17' E). A new bridge, the Hidasie Bridge, was dedicated 10 September 2008 at the presence of senior government officials and other guests. Funded by the Japanese government at a cost of 319.3 Birr, the Hidasie Bridge is 303 meters long and part of the new Addis Ababa-Dejen road. Experts foresee that improvements like the new bridge will allow drivers to double their speed to 60 kilometers per hour, and increase the volume of vehicles from the current 360 a day to 729 in six years. The new bridge sits alongside the older one over the Abay which had been built by the Italian government as part of their war reparations for their occupation of Ethiopia during World War II, and was about 60 years old when the new one was opened.