SP4

SP4 may refer to:

SP4, an album by Sneaker Pimps
Sp4 transcription factor, a human gene
Savoia-Pomilio SP.4, a reconnaissance and bomber aircraft built in Italy during the First World War
The Saint Patrick's Day Four
Service pack 4 in computing
Specialist Four (incorrectly called Specialist 4th class), a former enlisted rank of the U.S. Army, now simply Specialist
a model of steam toy made by British manufacturer Mamod
a 7.62×42mm silent pistol cartridge
Surface Pro 4, a laplet by Microsoft