GRO or Gro may mean:
- Tom Clancy's Ghost Recon Online
- Compton Gamma Ray Observatory
- General Register Office
- Girona-Costa Brava Airport (IATA code)
- Green River Ordinance, an American rock band from Fort Worth, TX.
- GRO, the three-letter station code for the Greensboro, North Carolina Amtrak station
- Gro, a variant of Gróa, the wife of Aurvandil the Bold in Norse mythology
- Guest Relations Officer, a bargirl euphemism.