Fio

Fio or FIO may refer to:
 * Fio Zanotti (born 1949), Italian record producer
 * FIO (software), the flexible IO tester created by Jens Axboe
 * Florida Institute of Oceanography
 * Fraction of inspired oxygen
 * Flexible IO
 * National Federation Of Industrial Organisations, former Japanese trade union federation
 * Pemoline, a stimulant
 * The East Slavic name format of family name, given name and patronymic (фамилия, имя, отчество – ФИО)
 * Free In and Out, maritime freight rate term