RPN may refer to:

Mathematics

• Reverse Polish notation, a.k.a. postfix notation, a mathematical notation
• ${\displaystyle \mathbb {R} \mathrm {P} ^{n},}$ real projective space

Nursing

• Registered practical nurse
• Registered psychiatric nurse

Other uses

• Radio Philippines Network, Channel 9
• Rancangan Perumahan Negara (National Housing Programme), public housing in Brunei
• Recherche en Prévision Numérique, weather forecasting researcher, Canada
• Registered Parameter Number, in MIDI
• Risk Priority Number, in failure analysis
• Rosh Pina Airport (IATA code), Israel