| Name | Phone | Location | District |
| O'Hoy K Y Katherine Dr | 2895 3221 | Hang Lung Centre | Causeway Bay |
| O'Reilly Brian J Dr | 2522 2721 | Prince's Bldg | Central District |
| On Shi Chiu | 2389 7976 | Hing Tat Mans | Kwun Tong |
| Ong Chang In Dr | 2760 8039 | Tokwawan Kai Fong Welfare Assn | To Kwa Wan |
| Ong Hak Wing Dr | 2351 0880 | Lung Poon Ct Coml Complex | Diamond Hill |
| Ooi Seng Poy Dr | 2366 1888 | Mohan's Bldg | Tsim Sha Tsui |
| Or Hing Chuen Dr | 2406 8282 | Hoi Ming Mans | Tsuen Wan |
| Oram & Partners Dr | 2522 7150 | Bank Of America Tower | Central District |
| Orr Wing Yam Dr | 2570 5785 | Kin Wah Bldg | Tai Hang |