HSO may refer to:
Orchestras Harrisburg Symphony Orchestra, Pennsylvania, United States Hartford Symphony Orchestra, Connecticut, United States Helena Symphony Orchestra, Montana, United States Hereford String Orchestra, England Hillsboro Symphony Orchestra, Oregon, United States Hollywood Symphony Orchestra, California, United States Houston Symphony, Texas, United States Huntsville Symphony Orchestra, Alabama, United States
Other uses Ford HSO engine Hamburg State Opera Health Sciences Online Healthscope, an Australian hospital operator Herschel Space Observatory Hungarian Space Office