Arsi (or Arssi) is one of the zones of the Oromia Region in Ethiopia. Arsi is also the name of a former province. Both the Zone and the former province are named after a subgroup of the Oromo, who inhabit both. Arsi is bordered on the south by Bale, on the southwest by the West Arsi Zone, on the northwest by East Shewa, on the north by the Afar Region and on the east by West Hararghe. The highest point in Arsi is Mount Chilalo; other notable mountains in this zone include Mount Kaka and Mount Gugu. The administrative center of this zone is in Asella; other towns in this zone include Abomsa, Assasa, Bokoji, Sagure, Kersa, Dhera, Etaya, Arsi Robe, Huruta etc. Some woredas at the southern part of zone were separated from Arsi zone to create West Arsi Zone.
Coffee has been a major cash crop in Arsi as early as 1912, when two Belgian companies were granted concessions of 1,464 hectares of land for cultivating coffee in the area of the current Zone. After World War I, these companies encountered financial difficulties and merged, and harvested as much as 613 tons of coffee at their peak (1931-21). The Central Statistical Agency (CSA), reported that 2198 tons of coffee were produced in this zone in the year ending in 2005, based on inspection records from the Ethiopian Coffee and Tea authority. This represents 1.9% of the Region's output and 0.97% of Ethiopia's total output. Arsi University is established recently at Asella. 
Based on the 2007 Census conducted by the CSA, this Zone has a total population of 2,637,657, of whom 1,323,424 are men and 1,314,233 women; with an area of 19,825.22 square kilometers, Arsi has a population density of 133.05. While 305,701 or 11.59% are urban inhabitants, a further 7,098 or 0.27% are pastoralists. A total of 541,959 households were counted in this Zone, which results in an average of 4.87 persons to a household, and 523,342 housing units. The two largest ethnic groups reported were the Oromo (84.15%) and the Amhara (14.3%); all other ethnic groups made up 1.55% of the population. Oromiffa was spoken as a first language by 81.38% and Amharic was spoken by 17.76%; the remaining 0.86% spoke all other primary languages reported. The majority of the inhabitants were Muslim, with 58.1% of the population having reported they practiced that belief, while 40.01% of the population professed Ethiopian Orthodox Christianity and 1.43% of the population professed Protestantism.
The 1994 national census reported a total population for this Zone of 2,217,245 in 438,561 households, of whom 1,105,439 were men and 1,111,806 women; 216,413 or 9.76% of its population were urban dwellers at the time. The two largest ethnic groups reported in Arsi were the Oromo (82.93%), and the Amhara (15.38%); all other ethnic groups made up 1.69% of the population. Oromiffa was spoken as a first language by 80.01%, and 19.19% spoke Amharic; the remaining 0.8% spoke all other primary languages reported. The majority of the inhabitants were Muslim, with 59.33% of the population having reported they practiced that belief, while 39.95% of the population said they professed Ethiopian Orthodox Christianity.
According to a May 24, 2004 World Bank memorandum, 4% of the inhabitants of Arsi have access to electricity, this zone has a road density of 45.0 kilometers per 1000 square kilometers (compared to the national average of 30 kilometers), the average rural household has 1.2 hectare of land (compared to the national average of 1.01 hectare of land and an average of 1.14 for the Oromia Region) and the equivalent of 1.1 heads of livestock. 16.5% of the population is in non-farm related jobs, compared to the national average of 25% and a Regional average of 24%. Concerning education, 84% of all eligible children are enrolled in primary school, and 22% in secondary schools. 17% of the zone is exposed to malaria, and none to Tsetse fly. The memorandum gave this zone a drought risk rating of 364.
- Richard Pankhurst, Economic History of Ethiopia (Addis Ababa: Haile Selassie I University, 1968), p. 203
- CSA 2005 National Statistics Archived November 23, 2006, at the Wayback Machine., Table D.2
- Census 2007 Tables: Oromia Region Archived November 13, 2011, at the Wayback Machine., Tables 2.1, 2.4, 2.5, 3.1, 3.2 and 3.4.
- 1994 Population and Housing Census of Ethiopia: Results for Oromia Region, Vol. 1, part 1 Archived November 15, 2009, at the Wayback Machine., Tables 2.1, 2.7, 2.12, 2.15, 2.17 (accessed 6 April 2009).
- "Ethiopia - Second Road Sector Development Program Project", p.3 (World Bank Project Appraisal Document, published 19 May 2003)
- Comparative national and regional figures comes from the World Bank publication, Klaus Deininger et al. "Tenure Security and Land Related Investment", WP-2991 (accessed 23 March 2006).
- World Bank, Four Ethiopias: A Regional Characterization (accessed 23 March 2006).