BSN is a three-letter abbreviation that may refer to:
- Biotechnology Society of Nepal, a Non-profit Biotechnology Organization
- Baloncesto Superior Nacional, basketball league in Puerto Rico
- Bank Simpanan Nasional, the government-owned bank in Malaysia
- The French food and beverage company Boussois-Souchon-Neuvesel (Groupe Danone since 1994)
- Bachelor of Science in Nursing
- Bassoon
- Blue Square North, the current sponsored name of one of the two leagues that form the second-highest level of non-league football in England
- Body sensor network
- Burgerservicenummer
- A school, The British School in the Netherlands
- Broadcasting System of Niigata, a Japanese TV station
- Bioware Social Network