OAP

OAP may refer to:
 * OAP Tower, or Osaka Amenity Park Tower, a plaza and office development in Japan
 * Old-age pensioner, a person who has retired, and now collects a pension, commonly referred to as an OAP in the United Kingdom
 * One Australia policy, a proposal in the 1980s to limit Asian immigration to Australia
 * Open access (publishing), a type of academic publication accessible by all, without subscription
 * Offset Alpine Printing
 * Off-axis parabolic reflector, a type of curved mirror used in optics and radio
 * the Office of Atoms for Peace of Thailand