S39 may refer to:

Aviation

* Blériot-SPAD S.39, a French reconnaissance aircraft * Letov Š-39, a Czechoslovakian sport aircraft * Prineville Airport, in Crook County, Oregon, United States * Sikorsky S-39, an American flying boat

Other uses

* S39: Wear eye/face protection, a safety phrase * New Jersey Route 68, designated Route S39 until 1953 * Sulfur-39, an isotope of sulfur * , a submarine in the United States Navy {{Letter-NumberCombDisambig