| ONCO LIMITED | Private company limited by shares | Dissolved |
| ONCO INVESTMENT LIMITED | Private company limited by shares | Dissolved |
| ONCO-BIOLOGICS LIMITED | Private company limited by shares | Dissolved |
| JAC Oncocare Limited | | Live |
| OncoImmune (HK) Holding Limited | Private company limited by shares | Live |
| Oncoimmunostics Limited | | Live |
| ONCOINN CAPITAL LIMITED | Private company limited by shares | Live |
| ONCOLE LIMITED | Private company limited by shares | Dissolved |
| ONCOLINK LIMITED | Private company limited by shares | Live |
| Oncologie Asia Limited | Private company limited by shares | Live |
| HONG KONG ASSOCIATION OF COMMUNITY ONCOLOGISTS LIMITED | Private company limited by shares | Live |
| SC ONCOLOGY COMPANY LIMITED -THE- | Private company limited by shares | Live |
| KOL ONCOLOGY LIMITED | Private company limited by shares | Live |
| THE Oncology Company Limited | | Live |
| AMO ONCOLOGY CENTRE LIMITED | Private company limited by shares | Live |
| Anchor Oncology Hematology Centre Limited | Private company limited by shares | Live |
| Hong Kong Integrated Oncology Centre (Kowloon) Limited | Private company limited by shares | Live |
| Queen's Road Oncology Centre Limited | Private company limited by shares | Live |
| CLINICAL ONCOLOGY GROUP LIMITED | Private company limited by shares | Live |
| Carbone Oncology Medical Consulting Limited | Private company limited by shares | Dissolved |
| ELEKTA ONCOLOGY SYSTEMS ASIA LIMITED | Private company limited by shares | Dissolved |
| Global Collaborative Oncology Group Limited | | Live |
| Gordian Oncology HK Limited | | Live |
| Hong Kong Integrated Oncology Centre Limited | Private company limited by shares | Live |
| Hong Kong Integrative Oncology Centre Limited | Private company limited by shares | Live |
| Hong Kong Precision Oncology Centre Limited | | Live |
| Centre for Oncology and Immunology Limited | Company limited by guarantee | Live |
| GBA Oncology Medical Centre Limited | Private company limited by shares | Live |
| ASSOCIATION OF ASIA-PACIFIC IMAGE-GUIDED MINIMALLY INVASIVE THERAPY IN ONCOLOGY LIMITED -THE- | Company limited by guarantee | Live |
| Neovia Oncology Limited | Private company limited by shares | Live |
| Asian School of Oncology Limited | Private company limited by shares | Live |
| HONG KONG PRECISION ONCOLOGY SOCIETY LIMITED | Company limited by guarantee | Live |
| ST. TERESA'S HOSPITAL ONCOLOGY CENTRE COMPANY LIMITED | Private company limited by shares | Live |
| Harvest Veterinary Oncology Centre Limited | Private company limited by shares | Live |
| H Wong Oncology Consultancy Limited | Private company limited by shares | Live |
| ONCOMED LIMITED | Private company limited by shares | Live |
| ON-COMING ENTERPRISE LIMITED | Private company limited by shares | Dissolved |
| ONCON GROUP LIMITED | Private company limited by shares | Dissolved |
| ONCOR ASIA LIMITED | Private company limited by shares | Dissolved |
| ONCOR ENTERPRISE LIMITED | Private company limited by shares | Dissolved |
| ONCOR INVESTMENT LIMITED | Private company limited by shares | Dissolved |
| ONCOR SUNJOINT LIMITED | Private company limited by shares | Dissolved |
| ONCOR SYSTEMS LIMITED | Private company limited by shares | Dissolved |
| ONCORE (AA) ENTERPRISES LIMITED | Private company limited by shares | Dissolved |
| OnCore Holdings Limited | Private company limited by shares | Live |
| OncoSeek Limited | Private company limited by shares | Live |