SEF may refer to:

• Sankara Eye Foundation, a non-profit that works for eradicating curable blindness in India
• Serviço de Estrangeiros e Fronteiras, Portuguese Border and Alien Service
• Sinfonia Educational Foundation, the philanthropic arm of the Phi Mu Alpha Sinfonia Music Fraternity
• Small Enterprise Foundation, a microfinance institution operating primarily in the Limpopo province of South Africa
• South Eastern Freeway, a Freeway in Australia
• Special Emergency Force, A Saudi Arabian riot control and counter-terrorism force
• Spectral edge frequency, a measure used in signal processing
• Stadio Erinis & Filias, the Greek name for Peace and Friendship Stadium, an indoor sports arena in Athens
• Straits Exchange Foundation, a semi-official organization of Taiwan that deals with the business matters with China
• Supplementary eye fields, areas in the primate brain that are involved in planning and control of saccadic eye movements
• Swap Execution Facility, a platform for regulated trading and clearing of swaps to be required in the United States by the Dodd-Frank bill
• Swedish Elite Football
• Swedish Electricians' Union, a trade union in Sweden
• Seaford railway station (England), a railway station in Sussex, England

See also:

• Sef, Iran (disambiguation)
• Sef Gonzales, Asian-Australian murderer