AT17 or AT-17 may mean:

• Hexachlorophene, an organic chemical that was used as an antiseptic and also in agriculture

• Cessna AT-17, a military training aircraft of World War II

At 17 may refer to:

• at17, a Hong Kong cantopop band

• At Seventeen, a 1975 song by Janis Ian and covered in 2013 by Celine Dion