BNF may refer to:
Science Backus–Naur form, a formal grammar notation in computer science Biological nitrogen fixation British National Formulary, a drug reference manual β-Naphthoflavone, an organic compound
Organisations British Nutrition Foundation, a charity (BnF), the French national library
Political parties Balawaristan National Front, Pakistan Belarusian National Front () BPF Party, break-away group from 1993 () Botswana National Front British National Front
Other uses Big Name Fan, a well-known fan