| Ocelot Bio |
| OCLAD Engineering |
| OCMS Bio, LLC |
| Octant |
| Octave Bioscience |
| OCTIMET Oncology N.V. |
| Ocugen, Inc. |
| Oculogenex |
| Oculus Research |
| OcuTerra |
| Ocutrx Technologies International Ltd |
| OcyonBio |
| ODI Medical AS |
| OFD, LLC |
| Office of the National Coordinator for Health Information Technology |
| Offor Health, Inc. |
| Ogun State College of Health Technology, Ilese-Ijebu |
| OHMX.bio |
| Oisin Biotechnologies |
| Okami Medical |
| Okirine Bio |
| OKKO Health |
| Okogen, Inc. |
| Olaris, Inc. |
| Olea Medical S.A.S. |
| Oleander Medical Technologies |
| Olema Oncology |
| Oligo Factory |
| Oligomerix, Inc. |
| Olive Diagnostics |
| Olympic Ophthalmics, Inc. |
| Olympic Protein Technologies |
| Omaiven Health |
| Omega Medical Imaging, LLC |
| Omeros Corporation |
| Omeza |
| Omicsveu |
| Omiqa Bioinformatics GmbH |
| Omizzur, Inc. |
| OmniAb, Inc. |
| OmniBRx Technologies |
| Omniose |
| Omniox |
| OmniTier |
| OMRON Healthcare, Inc. |
| OncoC4 |
| Oncocross Co., Ltd |
| Oncocyte Corporation |
| Oncodesign Precision Medicine |
| Oncogenuity, Inc. |