HDN

HDN may refer to

Medicine

 * Hemolytic disease of the newborn, an alloimmune illness
 * Hydronephrosis, hydrostatic dilation of the kidney

Places

 * Harlesden station, England, station code
 * Yampa Valley Airport, Colorado, US, IATA code

Other

 * Hyperdimension Neptunia, a video game series
 * Hydrodenitrogenation, an industrial chemical process
 * Northern Haida language of North America, ISO 639-3 code
 * Philippine Human Development Network
 * Hdn., an abbreviation for the Greek grammarian Aelius Herodianus