ETO may refer to:
- Earth to orbit, the process or means of placing a payload into an orbit around the Earth
- Engineer to order, a production approach where once a confirmed order for products is received, products are built
- Ethylene oxide, an important industrial chemical
- ETO sterilizer (or ET sterilizer), a type of sterilizer for medical equipment
- European Theater of Operations, the term used in the United States to refer to US operations north of the Mediterranean coast, in the European Theatre of World War II
- Samuel Eto'o (born 1981), Cameroonian football player
- ETO, another name for RUNX1T1
- Eto Demerzel, a recurring character in Isaac Asimov's books
- Győri ETO KC, is a Hungarian women's handball club from Győr
- ETO Park, a multi-use stadium in Győr, Hungary
- Early termination option, a clause in sports contracts that allows players to forgo their option year
- Grant ETO, a phrase used by NGO, Non-Profit and community service organizations to measure productivity and penetration. Similar in many respects to traditional business use of P&L (Profit and Loss) and Productivity Evaluation and Tracking products and software. Some of the key companys in this area are TechSoup.org, dBarista.com, and Socialsolutions.com all of whom provide both FREE and paid solutions.