PA4

PA4 may refer to:
 * ALCO PA-4, a diesel locomotive
 * Paranormal Activity 4
 * Pennsylvania Route 4
 * Pennsylvania's 4th congressional district
 * Pitcairn PA-4 Fleetwing II, a biplane
 * PA4 paper; see Paper size
 * The PA4, a type of rolling stock used on the PATH train in New York and New Jersey